Monday, June 28, 2021

Trophic Encounter Tables

We had a fabulous chat yesterday on the Wandering DMs Sunday talk show about our favorite Content Generators, starting with the monster tables in Original D&D provided as a way to populate dungeons and wilderness with a minimum of DM effort.

On that note, here's another guest article by our friend Angela Black: can we use real-world Trophic levels as a way to structure our random-table ecology simulators?


I've recently become bothered by encounter tables that propose that a certain wilderness area might be infested with all manner of huge and lethal monsters. Perhaps I'm too literal, but when I see that this particular forest contains dragons and owlbears and displacer beasts and wargs and and and... I always ask myself, "what are the EATING?" I suppose the answer might be 'each other,' but that's oftentimes too glib for me. I frequently find myself wishing for a more 'realistic' model of what monsters live in a given area.

Fortunately, scientists are great at modeling all aspects of the real world, and this sort of thing is not exception. Ecologists use a concept called "trophic levels" to describe the flow of energy through a given environment, which incidentally gives us a nice model of the relationships between predators and prey. Without wading too deeply into the very complicated math of this fascinating concept, we can use it to gain some traction on a more realistic model of encounter tables for fantasy roleplaying.

To sum up the ideas at play very briefly, we can imagine a pyramid-shape divided into zones that are called Trophic Levels.

  • At the base, the largest level is Trophic Level 1, where we find plants that form the base of the ecological system. Plants are rarely - but not never! - threats to PCs, so we don't normally list all the plants in a given region on the encounter tables.
  • Just above this we have Trophic Level 2, where we find the herivores that feed on the lower level These tend to be small creatures and likewise not *usually* a threat to PCs, so we don't tend to put all the squirrels and rabbits and whatnot on the encounter tables, either.
  • Trophic Level 3 is for smaller predators that feed on the herbivores in Trophic Level 2, like foxes and weasels and whatnot. These are usually only threats to humans in the real world if they feel directly threatened or they are protecting their young.
  • The next level if Trophic Level 4, where we find predators who feed at least partially on other predators, like hawks that might eat foxes. The important observation here is that creatures that occupy Trophic Level 4 are accustomed to attacking other creatures that are in themselves dangerous, as long as those creatures seem vulnerable. That will be important for gaming!
  • Finally, at the very top, we have so-called "apex predators," who can and will prey on anything in the area. Not every region will have an apex predator, but if it does, the apex predator will present a clear threat to PCs!

Now, we can already make some observations that will inform our encounter tables. We can (for now) ignore anything that would live at Trophic Level 1 or 2 in our region. On the other hand, we must account for the creatures that live at levels 3 and 4, as well as the apex predator(s), if any.

But the populations at these trophic levels live in very predictable relationships - for instance, there can't be more creatures at level 4 than at level 3, unless the creatures at level 4 are vastly smaller (for some reason) than the ones at level 3. If creatures at level 3 were rare and creatures at level 4 were abundant, the creatures at level 4 would quickly run out of food!

Generally speaking, the ratio of creatures from Trophic Level N to Trophic Level N + 1 is 10:1 or thereabouts. This is a very rough gloss of the actual math, but it works for our purposes. This also assumes similar body mass, but we'll ignore that for now. This figure of 10:1 gives us a great starting point for roughing out an encounter table.

Let's start with creatures at Trophic Level 3, since anything at levels 1 or 2 will only present a threat to PCs under very rare circumstances. Let's look at the Temperate Wilderness Forest tables in the MMII to get some ideas.

We should start by picking out a handful of animals for Trophic Level 3. These are animals that feed largely on herbivores (though they may themselves be omnivores that also eat plants). Some good candidates from the table we're look at might be badgers, boars, poisonous toads, snakes, weasels, and wolves. That's a great start.

2Then we move on to Trophic Level 4. What are some creatures that might prey on (at least some of) those creatures? We should choose fewer of them, maybe about three or four. We'll pick bears, hawks, and - just to add a fantasy element - owlbears.

Finally, we should choose an apex predator (and it is recommended there not be more than one, but this rule can be broken with careful consideration). For fun, I'll say there are fire lizards in this forest. Found under "Lizard, Giant," in the Monster Manual, the fire lizard is essentially a drake, a very dragon-like creature that is not intelligent but more of an animal. It has 10 HD and can breathe fire so it can certainly fill the role of apex predator!

Now to create the table. Let's start by observing the ratios. Collectively, the creatures at level 4 should be approximately ten times more likely to be encountered than the apex predator, and likewise the creatures at level 3 should be approximately ten times more likely to be encountered than the creatures at level 4. Now, we can't quite accommodate that on a standard percentile table, but we can approximate with the following standard layout:

  • 1%: Apex Predator
  • 2% to 11%: all the creatures at level 4
  • 12% to 99%: all the creatures at level 3
  • 100%: everything else

This layout preserves a realistic relative frequency of encounters - it wouldn't make sense for fire lizards to be massively more common than, say, bears, or even wolves! Likewise, the creatures at a higher level should be more dangerous overall than creatures at a lower level.

If the DM wants to adjust some, a 1:5 ratio could be used without stretching credibility too much, leading to an alternate table layout as such:

  • 1% to 3%: Apex Predator
  • 3% to 18%: Level 4
  • 19% to 93%: Level 3
  • 94% to 100%: everything else

DMs may find this layout is more congenial to gameplay while still preserving the same general ratios.

Notes:

  • The strength of the apex predator can be a guide as to whether the land is ripe for settlement or destined to remain wilderness for the foreseeable future. It should be assumed that humans in a fantasy setting will, as they were in the real middle ages, attempting to clear land into which they hope to expand. In fantasy settings, however, there are things which can easily repel even determined groups of humans, and if the apex predator in a given environment is sufficiently difficult to kill, certain areas may remain uncleared and unused regardless of the wishes of the local civilization! For instance, a region where the apex predator is the lion may present danger, to be sure, but can eventually be cleared for use by determined humans. Compare this to a forest where the apex predators are phase spiders!"everything else" is a useful catch-all for the rare, miscellaneous encounters from levels 1 or 2 that might actually prove dangerous to PCs. For instance, AD&D has numerous dangerous plants, like whipweed or yellow musk creepers. These plants cannot be exceedingly common, however, or there'd be no creatures from level 1 left to eat the plants! Putting such encounters in "everything else" is a good way to model this.

  • Placement of intelligent humanoids requires some judgment. If the area is truly wilderness, the humanoids must either be non-cultivators (like ogres) or exceedingly rare. For instance, if the DM wants to include human bandits in the woods, it's probably best to list them as an option under "apex predator," since if humans were in the woods in any greater abundance, they'd have cleared out the other apex predators and started to tame the land. Goblins, however, who avoid the larger creatures and mostly live by trapping herbivores and small predators actually qualify for level 4!

  • The level of the encounter is a fine guide to the behavior of the creature encountered.
    • Creatures in level 3 are non-confrontational unless desperate or frightened - they will fight if their homes are invaded, their young threatened, or they are backed into a corner, but that's it. It may be that characters experienced in woodscraft can "defuse" an encounter with a creature at level 3.
    • Creatures at level 4 will only attack with an advantage - if the target is smaller and weaker, if the target is injured, or if the target is outnumbered. Again, goblins make a fine level 4 creature, don't they?
    • Apex predators can and will attack anything they choose, and are frequently good at stalking prey and assessing the danger they present. Apex predators may hunt singly or in groups, depending on type and, if semi intelligent or intelligent, may present a massive threat to PCs.

Delta back here again -- Personally, I think that's pretty nifty, and the solid real-world math being used as a foundation is the kind of thing that gives me really good results in the past. Would you consider using that as a basis for your tables?

Monday, June 21, 2021

Spells Through The Ages – Wizard Eye

Wizard casting magic eyeball through door at evil figure

Let's do a Spells Through the Ages! Here's one we haven't surveilled yet: the magic-user's all-purpose lookabout spell, wizard eye -- or, in later editions, arcane eye. How has this 4th-level divination spell evolved?

Original D&D

Wizard Eye: A spell which allows the user to send a visual sensor up to 24" away in order to observe the scene without himself moving. The "eye" is invisible. It moves 12"/turn. Duration: 6 turns.

This is a spell that never appeared on the battlefield in Chainmail Fantasy, so we begin with Original D&D Vol-1. Unsurprisingly, the spell text is less than 3 lines long in this book. 

As we'll see, the one or two constants for the spell are laid down thus: The eye is invisible, and the caster can see through it. Here the eye is pretty zippy in its movement (as fast a normal man can move), but has a limited maximum range -- these details will change later on.

Recall the general custom at this time, per Chainmail, is that "In order to cast and maintain any spell, a Wizard must  be both stationary and undisturbed by attack upon his person". So arguably the "without himself moving" language is a slightly-redundant reminder of that fact (which will get more formal phrasing later).

Expert D&D

Wizard Eye  
Range: 240'
Duration: 6 turns
 

This spell creates an invisible eye through which the caster can see. It is the size of a real eye and has infravision to 60'. The wizard eye will float through the air up to 120' per turn, but will not go through solid objects or move more than 240' away from the caster. The caster must concentrate to look through the eye.

Cook's Expert rules keep the same effective speed and range as in OD&D. That said, this is the first place where the rules for the spell use the phrase "concentrate" (presumably a formalization of the "without himself moving" clause in OD&D). 

Also, there are two additions made which are also echoed in 1E AD&D around the same time (possibly from coordination with Gygax): (1) the spell is given infravision, and (2) it can't go through solid objects, neither of which were dictated in OD&D.

Note that the spell is depicted in this book with a nifty piece of art by Jeff Dee (at top of this article). It's careful to show the eye going through a cracked-open door to spy on the villain on the other side. The eye there looks as big as a man's torso, even though the text says it's the size of a normal eye (perhaps a trick of perspective).

1st Ed. AD&D

Wizard Eye (Alteration)
Level: 4
Range:  0
Duration:  1 round/level
Area of Effect: Special
Components:  V, S, M
Casting Time:  1 turn
Saving Throw: None

Explanation/Description:  When this spell is employed, the magic-user creates an invisible sensory organ which sends visual information to him or her. The wizard eye travels at 3" per round, viewing an area ahead as a human would or 1" per round examining the ceiling and walls as well as the floor ahead and casually viewing the walls ahead. The wizard eye can "see" with infravision at 10', or it "sees" up to 60' distant in brightly lit areas. The wizard eye can travel in any direction as long as the spell lasts. The material component of the spell is a bit of bat fur.

In Gygax's 1E AD&D, wizard eye keeps the standard invisibility and sight -- and as seen in the Expert rules, it gains infravision. However, that infravision is of very limited range (only 10'), 

A number of other key changes are made here: First, the maximum range seen in OD&D/Expert is removed; but on the other hand, the speed is much reduced to a very slow 3" (like a super-encumbered man), or even less when carefully scanning surfaces. If an 8th-level magic-user casts the spell (one more than the minimum level to cast it), and it last 8 rounds, then the maximum distance is 24" -- the same as it was in OD&D (but increasing for higher-level wizards, of course).

The next year, the DMG added its customary errata:

Wizard Eye:  The ocular device magically formed has substance and it has form which might be detected (cf. INVISIBILITY). Solid objects prevent the passage of a wizard eye, although it can pass through a space no larger than a small mouse hole (about one-half inch diameter).

So here we have the clarification that solid objects block the eye, and that a small "mouse hole" is needed for passage. Interestingly, one can have a debate about exactly what constitutes a "mouse hole", because mice are flexible and can pass through very small holes. So should that be the size of a pencil, a dime, a ping-pong ball? (We actually had a small debate about this years ago in the comments on this article.)

Consider also the reference to the "INVISIBILITY" rules in that book. As a standard rule at the time, high-level (hit dice 7+) and intelligent creatures had a percentage chance to automatically detect invisible entities -- including the wizard eye, presumably.

2nd Ed. D&D

Wizard Eye
(Alteration)
Range: 0
Duration: 1 rd./level
Area of Effect: Special
Components: V, S, M
Casting Time: 1 turn
Saving Throw: None

When this spell is employed, the wizard creates an invisible sensory organ that sends him visual information. The wizard eye travels at 30 feet per round if viewing an area ahead as a human would (i.e., primarily looking at the floor), or 10 feet per round if examining the ceiling and walls as well as the floor ahead. The wizard eye can see with infravision up to 10 feet, and with normal vision up to 60 feet away in brightly lit areas. The wizard eye can travel in any direction as long as the spell lasts. It has substance and a form that can be detected (by a detect invisibility spell, for instance). Solid barriers prevent the passage of a wizard eye, although it can pass through a space no smaller than a small mouse hole (1 inch in diameter).

Using the eye requires the wizard to concentrate. However, if his concentration is broken, the spell does not end--the eye merely becomes inert until the wizard again concentrates, subject to the duration of the spell. The powers of the eye cannot be enhanced by other spells or items. The caster is subject to any gaze attack met by the eye. A successful dispel cast on the wizard or eye ends the spell. With respect to blindness, magical darkness, and so on, the wizard eye is considered an independent sensory organ of the caster.

The material component of the spell is a bit of bat fur.

As is customary, Cook's 2E AD&D revision sticks very closely to the 1E rules text, and incorporates the extra language previously seen in the DMG. He again uses the word "concentrate", like he used back in the Expert D&D rules (but was not used in Gygax's 1E). The movement and infravision range are still very low. The necessary "mouse hole" size has doubled from a half-inch to a full inch (roughly the size of an actual human eyeball -- did Gygax previously assume the wizard eye was squishy and could squeeze through a hole smaller than itself? Think of me kindly when you reflect on that this week.)

The 2nd paragraph here adds more details to handle various exceptional cases: Gaze attacks can pass detrimentally through the eye. The eye itself can't be buffed or blinded by other spells (except via dispelling). And it looks like a wizard can use this to get around themselves being blinded, because it is stipulated as being an "independent sensory organ".

3rd Ed. D&D

Arcane Eye
Divination
Level: Sor/Wiz 4
Components: V, S, M
Casting Time: 10 minutes
Range: Unlimited
Effect: Magical sensor
Duration: 1 minute/level
Saving Throw: None
Spell Resistance: No

The character creates an invisible magical sensor that sends the character visual information. The arcane eye travels at 30 feet per round (300 feet per minute) if viewing an area ahead as a human would (primarily looking at the floor) or 10 feet per round (100 feet per minute) if examining the ceiling and walls as well as the floor ahead. The arcane eye sees exactly as the character would see if the character were there. The arcane eye can travel in any direction as long as the spell lasts. Solid barriers prevent the passage of an arcane eye, although it can pass through a space no smaller than a small mouse hole (1 inch in diameter).

The character must concentrate to use the eye. If the character does not concentrate, the eye is inert until the character again concentrates. The powers of the eye cannot be enhanced by other spells or items (though the character can use magic to improve the character's own eyesight). The character is subject to any gaze attack met by the eye. A successful dispel magic cast on the character or the eye ends the spell. With respect to blindness, magical darkness, and other phenomena that affect vision, the arcane eye is considered an independent sensory organ of the character's.

Any creature with Intelligence 12 or higher can sense the arcane eye by making a Scry check or an Intelligence check (DC 20). Spells such as detect scrying can also detect the eye.


A major change in 3E is that wizard eye gets renamed arcane eye -- at the same time that the class previously known as "Magic-User" is renamed "Wizard", and other classes are given access to the same spells, such as the new "Sorcerer". (So: the spell isn't just for wizards anymore.)

Otherwise, the language of the spell is largely the same as in 2E: it retains basically the same sight, invisibility, low speed, no range limit, concentration requirement, vulnerability to gaze attacks, etc. Even the "small mouse hole (1 inch in diameter)" requirement is identical. 

One thing that you don't see here (unless I've been blinded) -- the infravision (now, darkvision) has been removed from the spell description for the first time since OD&D. Isn't that maybe highly limiting in a dark dungeon? Perhaps it's expected that the caster can magically give themselves darkvision to get around this issue -- re: "the character can use magic to improve the character's own eyesight" -- and yet doesn't that permission itself contradict the "independent sensory organ clause" retained from 2E?

Finally, note the last paragraph on highly-intelligent creatures getting an Intelligence (or Scry skill) check to detect the sensor. This mechanic is a replacement for the prior general rule that high-level and intelligent creatures can sense any invisible objects.

This spell doesn't appear at all in 4th Edition D&D (so far as I can tell), so we proceed to the 5th.

5th Ed. D&D

Arcane Eye
4th-level divination
Casting Time: 1 action
Range: 30 feet
Components: V, S, M (a bit of bat fur)
Duration: Concentration, up to 1 hour

You create an invisible, magical eye within range that hovers in the air for the duration.

You mentally receive visual information from the eye, which has normal vision and darkvision out to 30 feet. The eye can look in every direction.

As an action, you can move the eye up to 30 feet in any direction. There is no limit to how far away from you the eye can move, but it can’t enter another plane of existence. A solid barrier blocks the eye’s movement, but the eye can pass through an opening as small as 1 inch in diameter.

Commendably, 5th edition edits back the spell text a bit, in contrast to the bloat it received in editions 1-3. It's still invisible, slow, no maximum range, and has the exact same "1 inch diameter" requirement first seen in 2E. It returns the darkvision capacity that 3E removed. The extra corner-case language around independent-organ status, gaze attacks, etc., etc., has been removed, and left for adjudication by the individual and empowered DM.

Conclusions

Wizard eye is a spell that had its biggest shakeup in Gygax's 1E AD&D rules (changing speed, removing range, adding infravision, setting the "mouse hole" requirement, etc.) The extra bloated corner-case language circa 2E has come and gone. For me, I'm not fond of the 3E name change to arcane eye -- that kind of increased abstraction loses a lot of visceral feeling for me (here, replacing the imagination-catching "wizard" that anyone would recognize, for an in-game keyword "arcane" that only IP-trained players would fully understand).

Given the notable shift between Original and Advanced D&D, what are your preferences for wizard/arcane eye?

  • Fast or slow movement?
  • Limit to range or not?
  • Magical darkvision or not?
  • And how big is a "mouse hole", anyway?

 

Monday, June 14, 2021

Ever-Bewitching Charm

Following up on the charm person survey from last week, I asked a similar question on the ODD&4 forums (account required). A fascinating discussion ensued, and our colleagues over there have old-school research capacities that far outstrip my own. Here's a few of the remarkable insights that I felt should get a bigger amplification:

SebastianDM observes:

The interpretation of this effect seems to be one of the earliest issues of D&D. I was just reading some of the old issues of Alarums & Excursions and found that the very first discussion of the very first issue is related to this very issue. I read that the content of this issue was mainly reprinted from APA-L since it was the first issue, so I guess the discussion is from 1975 at the latest.

Debate in 1975 over charm person

Our friend Zenopus of Zenopus Archives points to Dragon Magazine #52, where J. Eric Holmes (author of the Original D&D Basic set) reviews the newfangled Moldvay B/X rules:

A charmed Magic-User is too confused to do magic? Boy, that last rule would make a dramatic change in the conduct of my game, where the player characters would be apt to yell, "Don’t kill the evil magician! Let me try to charm him first, then use him to wipe out the rest of the monsters on this level."

Poster acodispo points out that charm person is heavily baked into the OD&D rules section on hiring new NPCs (Vol-1, p. 12; before the nominal explanation of the spell itself), such that one could easily and solidly interpret it as an "instant hireling" spell:

Monsters can be lured into service if they are of the same basic alignment as the player-character, or they can be Charmed and thus ordered to serve. Note, however, that the term "monster" includes men found in the dungeons, so in this way some high-level characters can be brought into a character's service, charisma allowing or through a Charm spell. Some reward must be offered to a monster in order to induce it into service (not just sparing its life, for example). The monster will react, with appropriate plusses or minuses, according to the offer, the referee rolling two six-sided dice and adjusting for charisma...

Perhaps most interestingly, this thoughtful discussion is actually prompting some people to flip their prior interpretations, such as poster ampleframework here:

I think I'm starting to lean back towards the "total mind control" camp after seeing some of these arguments. It kind of makes sense. Magic was unbalanced in an awesome way in 3lbb. Maybe it's better to not invent limitations or justify later ones in this context. 

Fascinating stuff! Has the way you rule on charm person changed or evolved over the years?

Monday, June 7, 2021

Surveys & Samples: Charm Person

I've struggled with the D&D charm person spell for some time (c.f.: Charm Person Through the Ages). Partly that's due to what appears to be one of the most radical de-powerings of any spell in the first 3 editions or so. In OD&D it started out with the stated effect of:

... come completely under the influence of the Magic-User until such time as the "charm" is dispelled (Dispell Magic)... (Vol-1, p. 23)

But this "complete" control and infinite duration was rapidly nerfed with recurrent saving throws (Supplent I: Greyhawk), language that the victim merely considered the caster a "trusted friend and ally" (AD&D PHB), bonuses to saves in combat and other restrictions (AD&D DMG), etc. By the time of the 3.5 edition revision, it merely lasts 1 hour/level, and requires an additional Charisma check to convince the victim to do anything they wouldn't normally do anyway. 

Now, some claim that this is broadly the way it always was intended (but boy, that seems like a huge shift in the language to me). E.g., Mike Mornard, who played in both original campaigns by Gygax & Arneson, recalls:

"Charmed" means "Charmed, I'm sure." The person is now your new best friend. They are NOT your mindless slave. That's how Dave and Gary both played it. (ODD74; account required)

On the other hand: In the section on hiring NPCs, it is written: "... or they can be Charmed and thus ordered to serve" (Vol-1, p. 12); and charm person was also ability ascribed to monsters such as Vampires, Dryads, etc., who could dominate and, indeed, "enslave" a victim (see: Vol-2, Nixie) for a year or more each. In the AD&D DMG Gygax tried to carve a distinction between those abilities and the spell of the same name, saying they were very different; which seems more like a retcon than consistent intent. 

Related to this wide variation in power of the spell over the years, one of the things that really bugs me about charm person is how often it turns into a debate at the table over what its effect should be -- and how often players are surprised or disappointed at an effect they didn't expect. For a 1st-level spell, I dare say this is unique. Other low-level spells generally have a very clearly qualified effect that the caster will be aware of in advance. But here we have charm person at 1st level -- frequently the very first offensive spell that a new magic-user will take -- and it usually turns into a dispute or a "gotcha" upon casting it. 

For the brand-new D&D player, it seems likely that their first impression of magic is that it's all based purely on fiat rulings by the DM and how much you can sway them through argument. 

Facebook Poll

Wondering what the majority opinion was, I thought to ask a poll on the sizable Facebook AD&D group. Questions were first reviewed & edited by Patrons on the Wandering DMs Discord channel (thanks!). Here's the result:


There were a total of 158 different voters (note participants were directed to pick "all that apply", so generally multiple selections). Of the options presented, the vote totals were as follows:

  • Defend the caster -- 126 (80%)
  • Flee the encounter -- 80 (51%)
  • Surrender and disarm -- 68 (43%)
  • Attack former allies -- 35 (22%)
  • Nothing: charm fails in combat -- 12 (8%)

So only two of the given options received majority approval: Defending the caster seems clearly to be allowed, and fleeing the encounter gets the nod from a hairs-breadth over half of the respondents. Other options like surrender or go on the offensive for the caster got the thumbs-down.

I must say I actually am quite heartened by the interpretation that an enemy charmed in combat doesn't immediately start fighting on the magic-user's side -- even though that's how I always ruled it by default historically. That seemed to me to be following the letter of the rule, but it felt incredibly swingy. Losing any party member to a spell is one thing, but then the other side gaining the same figure, of course, makes for an immediate 2-person swing which can be quite brutal (esp., again, to a 1st-level spell; and moreso with modern small party sizes). 

(Contrast, though, to an example like the magic-user in J. Eric Holmes' Basic D&D sample dungeon: he has a fighter he holds under a charm person spell, and the first thing he does in an encounter is "(a) direct the fighter to attack", albeit probably not former allies. Or likewise the one in Frank Mentzer's Basic D&D dungeon; when the player misses a save vs. charm person, they immediately abandon the cleric with whom they were adventuring -- and who earlier referred to the effect as, "He has probably cast a spell on the goblin to force it to serve him".)

Other Suggestions

As is common, a large number of other intriguing suggestions were added in the discussion, as well as some objections to the premise of the poll in the first place. The most common redirection is that the effect of charm person is indeed entirely context-dependent, and will only be known after the result of role-playing interactions between the player and DM. (Which if you recall is part of my grief earlier). Some examples:

John D.
None of the above! The magic-user can't force the fighter to do anything. They can only make suggestions and the fighter will respond as if they viewed the caster as favorably as possible. All of these would depend on the context.

Keith W.
Can't force anything....but with some good roleplaying, I'd allow some of those. Nothing that causes harm to him or his allies, but I could see him trying to talk them out of killing the caster as they now view you as a friend.

Drew B.
This is where the magic user has to come up with some strong role playing for the spell to work.

Troy O.
Great opportunity to let player role play dialogue and the more convincing the “story” the better chance it will work to charm but not force. For example go kill dragon now vs spun story of why fighter needs to go kill dragon might work. Of course DM final say...

Adam V.
I think it depends on the charisma of the mage

And so forth. A few other interesting takes:

Chris T.
The big problem is how does the charmed fighter square the circle that his best friend and allies want harm / kill each other?

Daniel N.
Since the spell says you could convince someone to hold off a dragon (and surely die) I’d say it’s pretty powerful, level one or not.

Alan S.
How good is group communication and how noisy is the fight?...

Mark B.
Just bc he regards the caster as a dear friend doesn't mean he stopped regarding his former allies as they were. He wouldn't likely attack them for any reason

Jay G.
Mark B. you’re assuming the charmee likes and trusted his former allies. Why is that necessarily true, especially for evil opponents? And even if they do...when the charmee trusts the caster totally, if he tells him “your comrades are really evil doppelgangers! We need to kill them!”, why wouldn’t he believe him?

Conclusions

As noted earlier, I'm quite uncomfortable with the "depends on roleplay" interpretation, because ultimately it depends far more on DM attitude or mood that any comparable, frequently-used, low-level spell. My instinct is that lower-levels spells should be clearly defined and known quantities to the player. Higher-level spells I'm a lot more comfortable transitioning to murky effects that may surprise the player or have an effect unique to a particular DM's game world. Charm person at 1st level with a hugely slippery and unpredictable effect stands out as "proud nail" unlike anything around it.

I actually feel very prone to write explicitly into my effect for charm person, following the poll results, that it can definitely make a victim play defense/shield-man for the caster, or withdraw from the encounter -- but not throw down their arms, or attack former allies. The items on the far ends I'm most comfortable with; the ones near the 50% I'm just somewhat more sketchy about, but not unhappy to follow a consensus on those.

What do you think about those results?