Spells Through The Ages – Contact Other Plane

The contact other plane spell is the D&D equivalent of a Magic 8-Ball; the wizard player asks several "yes or no" questions, and receives answers of varying accuracy based on dice-rolls by the DM. Trivia: It's the only spell in the OD&D LBB's complicated enough to have an attached table for its effects, or to run more than a single paragraph in length. That table and its expressed probabilities changed in every later edition, so it seems perfect for the kind of analysis I do here. It's a spell that rarely gets used in most games, because the clerical commune does the same job without any chance of inaccuracy ("veracity and knowledge should be near total"; Vol-1, p. 33) -- but since I run a non-clerical game, contact other plane is potentially of much greater interest. For brevity in the discussion below, I will use N = the Nth planar option in the list (regardless of title, which changes in almost every edition; usually between 1 and 10).

Original D&D

Contact Higher Plane: This spell allows the magical-type to seek advice and gain knowledge from creatures inhabiting higher planes of existence (the referee). Of course, the higher the plane contacted, the greater the number of questions that can be asked, the greater the chance that the information will be known, and the higher the probability that the question will be answered truthfully. Use the table below to determine these factors, as well as the probability of the Magic-User going insane. Only questions which can be answered "yes" or "no" are permitted.

If a Magic-User goes insane, he will remain so for a number of weeks equal to the number of the plane he was attempting to contact, the strain making him totally incapacitated until the time has elapsed. For each level above the 11th, Magic-Users should have a 5% better chance of retaining their sanity. The spell is usable only once every game week (referee's option).

So among the first questions I've always had about Gygax's original contact higher plane spell is: Why does it only start at the "3rd" plane? My best guess is something like: 1st is "Underworld", 2nd is "Surface World", and then 3rd+ are the "Seven+ Heavens" or something like that (i.e., the "higher planes"). Maybe you have a better idea about that than I do?

But let's look at the probabilities expressed; the Knowledge and Veracity columns aren't perfectly regular, jumping by either 5% or 10% increments in different spots (usually more gradual 5%'s near the start or end). The Insanity column does increase by exactly 10% per step. Thus we can observe (recall that N=1 indicates the starting 3rd Plane and so forth):

• Knowledge ≈ N×10%
• Veracity ≈ (N+2)×10%
• Insanity = (N−1)×10%

Now, one thing that makes this spell really tough to use is that to get accurate information on any question you need to succeed at both the Knowledge and Veracity rolls (otherwise you get nothing, or incorrect information). Which is to say: You're at the mercy of the special multiplication rule of probability, which makes your chance of success drop below either of the individual components. Here's what you get for those products, that is, the actual chance of getting good information for each question:

• 3rd Plane: 7.5%, 4th: 12%, 5th: 17.5%, 6th: 24%, 7th: 35%, 8th: 45%, 9th: 56%, 10th: 68%, 11th: 81%, 12th: 95%.

So as you can see, the chance of getting correct answers is practically negligible at any of the lower levels (3rd-5th Planes). In order to get past 50% (i.e., more right than wrong answers), you need to contact at least the 9th Plane -- at which point the chance of insanity is also more than half (60%), that is, you're resigned to probably going insane and not even getting to ask any questions in the first place (modified by caster levels above 11th, much like magic resistance). In summary: It's hard to avoid saying that this spell isn't flat-out broken. You're incredibly likely to go temporarily insane, and if you don't, then in most cases you'll get far more wrong answers than right answers.

Edit: A possible explanation for the range of planes given (or at least the upper bound) -- In L. Sprague de Camp's The Fallible Fiend, the protagonist "demon" in question is said to be summoned to the Prime Plane from the Twelfth (see the very first paragraph of the book). So likely this was an initial inspiration for much of our terminology on planes, and why the table above indeed goes up to the 12th. Still no clue as to why it starts at the 3rd, however.

D&D Expert Rules

Contact Higher Plane
Range: 0'
Duration: see below

This spell allows the caster to contact a higher plane and seek knowledge from strange and powerful creatures (played by the DM). The chart below lists the planes the caster can contact, how many yes or no questions a creature of it will answer, what its chance of knowing the answer is, how often the creature will lie, and what risk of insanity the caster takes contacting the plane. There is no way of knowing if the creature is lying. For every level above 11th, there is 5% less chance of insanity (thus a 12th level magic-user would have 5% less chance of going insane than indicated on the table shown).

This spell can be used once a week (or less often at the DM's option). Characters going insane recover after a number of weeks of game time equal to the number of the plane contacted. Thus, a person contacting the eighth plane would be out of the campaign for 8 weeks. The caster selects the plane to be contacted.

For Dave Cook's first take on interpreting Gygax, as usual he keeps the spell as much like the OD&D text as he can. The "Knowledge" chance is identical to OD&D. He's inverted the "Veracity" chance to what's here "Chance of Lying", and as he did that, he also smoothed out the progression to exactly 5% per step (resulting in a generally greater chance of veracity than in OD&D). He's also radically reduced the "Insanity" chance to only 5% per level, instead of OD&D's 10% per step. In summary the system here is:

• Knowledge ≈ N×10%
• Veracity = (N+9)×5%
• Insanity = N×5%

Checking on multiplied products for good information with each question:

• 3rd Plane: 12.5%, 4th: 16.5%, 5th: 21%, 6th: 26%, 7th: 35%, 8th: 45%, 9th: 56%, 10th: 68%, 11th: 81%, 12th: 90.3%.

With the small changes that Cook made, these chances are somewhat improved at the lower levels (3rd-5th Planes), but they're still all less than 25%, and thus pretty much not useful as options at all. The higher level (7th-11th) are all identical to OD&D, with the 12th Plane marginally reduced. At least with the reduction in Insanity chance, you're more likely to actually get to use the spell, no matter what Plane you pick in this system. So that's something.

AD&D 1st Ed.

Contact Other Plane (Divination)
Level: 5
Range: 0
Duration : Special
Area of Effect: Special
Components: V
Casting Time: I turn
Saving Throw: None

Explanation/Description: When this spell is cast, the magic-user sends his or her mind to another plane of existence in order to receive advice and information from powers there. As these powers are located at random, and resent such contact in any case, only brief answers will be given. (Your DM will answer all questions with a "yes", "no", "maybe", "never", "irrelevant", etc.) The character can contact an elemental plane or some plane further removed. For every 2 levels of experience of the magic-user one question may be asked. Contact with minds far removed from the plane of the magic-user increases the probability of the spell caster going insane or dying, but the chance of the power knowing the answer, as well as the probability of the being telling the correct answer, are likewise increased by moving to distant planes:

* For every. 1 point of intelligence over 15, the magic user reduces probability of insanity by 5%.

** If the answer is unknown, and the answer is not true, the being will answer definitely. If truth is indicated, it will answer "unknown."

***Assumes knowledge of questions pertaining to the appropriate elemental plane.

Insanity will strike as soon as 1 question is asked. It will last for 1 week for each removal of the plane contacted, 10 weeks maximum. There is a 1% chance per plane that the magic-user will die before recovering unless a remove curse spell is cast upon him or her.

By AD&D, Gygax seems to have been convinced that the spell needs some significant fix-ups. Here are the highlights of those changes:

1. He changes the name to contact other plane (AD&D having now fleshed out the Gygaxian "Great Wheel" cosmology in early Dragon articles and the PHB Appendix, such that there are now both "higher" and "lower" planes that should reasonably be accessible by both good and evil wizards). 
2. He's changed the names of the options, fixing that confusing start at the "3rd Plane", and now instead starting at "1 removed" (although now I'll ignore that anomalous "Elemental" option; below N=1 indicates "1 removed", et. al.). 
3. He seems to agree with Cook on the reduced Insanity chances, duplicating them exactly as they appeared in the Expert Rules (and also moving that column first, which makes sense, because it's really the first thing you'd have to check as the spell commences). 
4. On the other hand, he's removed the standard 5% modifier per level above 11th vs. insanity, replacing it with a 5% improvement per Intelligence above 15, which is likely to be a much smaller modifier (at most +3 steps in PHB rules; see single-asterisk note above). 
5. He's changed the Knowledge chance to a straight 5% increase per step, and greatly increases the base chances at the lower levels over either OD&D or B/X (which were equal).
6. He's likewise massively increased the Veracity chance over OD&D or B/X, more than doubling it in the starting "1 removed" (old 3rd Plane) category.
7. He's also changed the number of questions from the Planar number to a formula based on caster level, namely Questions = Level/2 (thus abbreviating the table a little bit).
8. He's added some specification to what happens if both the Knowledge and Veracity checks fail at the same time (namely, the spell lies and claims either "yes or no" -- presumably the opposite of the facts, otherwise this would wind up accidentally revealing correct information in a fail-fail situation; see the double-asterisk note).
9. And there's a chance of caster death, following insanity, unless the user has an ally with remove curse nearby at the ready (maybe to make casters less blasé about using the spell casually and waiting out the insanity periods?).

In the DMG there's a note (p. 45) referring users of this spell to the new section on "Insanity" for specific options if things go awry here. So having said that, the overall system is now equivalent to (with irregularities only at the terminating 9+ level):

• Knowledge = (N+11)×5%
• Veracity = (N+20)×3%
• Insanity = N×5%

And the products for truthful information per question work out as follows:

• 1st Removed: 39.0%, 2nd: 43.6%, 3rd:49.0%, 4th: 54.8%, 5th: 60.0%, 6th: 66.3%, 7th: 72.9%, 8th: 80.8%, 9th+: 88.2%.

This is clearly improved from the user's perspective. There's no option with less than a one-third chance of correct answers; picking a plane where you'll get more correct answers (4th+) still has a low chance of insanity (20%; or just 5% after being modified for an 18 Int, say). I think a partisan can still reasonably argue that the contact other plane may be underpowered, but at least by this point I wouldn't tell a fellow player to hands-down avoid using the spell under any circumstances.

AD&D 2nd Ed.

Contact Other Plane
(Divination)
Range: 0
Duration: Special
Area of Effect: Special

When this spell is cast, the wizard sends his mind to another plane of existence in order to receive advice and information from powers there. As these powers resent such contact, only brief answers are given. (The DM answers all questions with "yes," "no," "maybe," "never," "irrelevant," etc.) Any questions asked are answered by the power during the spell's duration. The character can contact an elemental plane or some plane farther removed. For every two levels of experience of the wizard, one question may be asked. Contact with minds far removed from the plane of the wizard increases the probability of the spellcaster going insane or dying, but the chance of the power knowing the answer, as well as the probability of the being telling the correct answer, are likewise increased by moving to distant planes. Once the Outer Planes are reached, the Intelligence of the power contacted determines the effects.

The accompanying random table is subject to DM changes, development of extraplanar NPC beings, and so on.

If insanity occurs, it strikes as soon as the first question is asked. This condition lasts for one week for each removal of the plane contacted (see the DMG or the Planescape™ Campaign Setting boxed set), to a maximum of 10 weeks. There is a 1% chance per plane that the wizard dies before recovering, unless a remove curse spell is cast upon him. A surviving wizard can recall the answer to the question.

On rare occasions, this divination may be blocked by the action of certain lesser or greater powers.

* For every point of Intelligence over 15, the wizard reduces the chance of insanity by 5%.

** If the being does not know an answer, and the chance of veracity is not made, the being will emphatically give an incorrect answer. If the chance of veracity is made, the being will answer "unknown."
 
Percentages in parentheses are for questions that pertain to the appropriate elemental plane.
 
Optional Rule
The DM may allow a specific Outer Plane to be contacted (see the Planescape Campaign Setting boxed set). In this case, the difference in alignment between the caster and the plane contacted alters the maximum Intelligence that can be contacted--each difference in moral or ethical alignment lowers the maximum Intelligence that can be contacted by 1. For example, an 18th-level lawful good caster could contact Mount Celestia (a lawful good plane) on the "Intelligence 20" line, or Elysium (a neutral good plane) on the "Intelligence 19" line.

And here's Cook's second swing at interpreting & updating the works of Gygax. The overall mechanic, and the chances for both "Knowledge" and "Veracity" are totally identical to 1E. But he's significantly increased the chance of Insanity, adding +20% over what was used in both 1E and his own Expert rules; that seems unwarranted, and I'm kind of mystified by why he did that for this spell (maybe feeling he had to counter-balance the Int bonus that was added in 1E?). He gives a "mulligan" to the unfortunate caster, by letting him or her return from insanity with the answer to 1 question in their mind from using this spell.

But the biggest noticeable change here is a flavor-text makeover, now that the Great Wheel has been further fleshed out in later AD&D works like Deities & Demigods, the Manual of the Planes, and the Planescape campaign setting (which is given two shout-outs in the text above). At this point, it's been established that major and minor powers may hold dominion throughout the various planar levels -- it's not strictly just higher-is-better. And therefore Cook is compelled to switch from the simple "planar level" dial to one which specifies entities of different mega-Intelligence, regardless of what planar level they're on. Also he adds the "Optional Rule" that caster alignment interacts with what level of Intelligence they're allowed to contact on each Outer Plane. So that sort of makes sense, but for my money it starts entangling too many issues at once for the spell to be quickly comprehensible (esp. by newer players that don't have prior understanding of the "Great Wheel" cosmology... and after all, the "Optional Rule" just implies you should contact your alignment's plane, with no other side-effects from that fact). In any case, as stated earlier, the actual game-mechanics are effectively the same as before.

So the probability system is the same as 1E except for the increased "Insanity" chances (N=1 for "Inner Plane", etc.):

• Knowledge = (N+11)×5%
• Veracity = (N+20)×3%
• Insanity = (N+4)×5%

And the truth-per-question chances are exactly the same as 1E (see above). However, to break 50% odds for correct answers, you need to pick a contact  (N=4, "4 removed" in 1E, "Outer Plane, Int 20" here) where you're almost equally likely to go insane before asking your first question (specifically, 40% or higher). So I can live with the flavor-text changes, but I'm wondering if Cook regrets that increase to the Insanity chances.

D&D 3rd Ed.

Contact Other Plane
Divination
Level: Brd 5, Sor/Wiz 5
Components: V
Casting Time: 10 minutes
Range: Personal
Target: The character
Duration: Concentration
The character sends his or her mind to another plane of existence in order to receive advice and information from powers there. (See the accompanying table for possible consequences and results of the attempt.)

Avoid Effective Intelligence/Charisma Decrease: The character must succeed at an Intelligence check against this DC in order to avoid effective Intelligence and Charisma decrease. If the check fails, the character's Intelligence and Charisma scores fall to 8 for the stated duration, and the character becomes unable to cast arcane spells. If the character loses Intelligence and Charisma, the effect strikes as soon as the first question is asked, and no answer is received. (The entries in parentheses are for questions that pertain to the appropriate Elemental Plane.)

Results of a Successful Contact: The DM rolls d% for the result shown on the table:

• True Answer: The character gets a true, one-word answer. Questions not capable of being answered in this way are answered randomly.
• Don’t Know: The entity tells the character that it doesn’t know.
• Lie: The entity intentionally lies to the character.
• Random Answer: The entity tries to lie but doesn’t know the answer, so it makes one up.

The powers reply in a language the character understands, but they resent such contact and give only brief answers to the character's questions. (The DM answers all questions with "yes," "no," "maybe," "never," "irrelevant," or some other one-word answer.) The character must concentrate on maintaining the spell (a standard action) in order to ask questions at the rate of one per round. A question is answered by the power during the same round. For every two caster levels, the character may ask one question.

The character can contact an Elemental Plane or some plane farther removed. Contact with minds far removed from the character's home plane increases the probability of suffering an effective decrease to Intelligence and Charisma, but the chance of the power knowing the answer, as well as the probability of the being telling the correct answer, are likewise increased by moving to distant planes. Once the Outer Planes are reached, the power of the deity contacted determines the effects.

On rare occasions, this divination may be blocked by an act of certain deities or forces.

So in Jonathan Tweet's 3E Player's Handbook, the spell is broadly similar (much of the text is copy-and-pasted from before), but the main mechanical change is that the double-roll for Knowledge and Veracity has been collapsed into a single roll on the table above that incorporates all the different possibilities. The last column, "Random Answer" is defined in the note as "entity tries to lie but doesn’t know the answer, so it makes one up". That's equivalent to our previous double-fail condition, although the 3E designers are interpreting that differently than I did above, apparently allowing for the accidental-truth possibility (which I guess makes sense; maybe I should use that myself).

The flat percentage "Insanity" chance has been replaced by an Intelligence check under these rules at some specified DC. Assuming that the caster has an Intelligence of 15 (like the basis for 1E/2E), then I calculate the chances for failing this insanity-like check as follows:

• N=1 ("Positive/Negative Energy Plane"): 25%, 2: 30%, 3: 35%, 4: 45%, 5: 55%, 6: 65%.

And this is actually identical to how Cook's 2E chart for Insanity starts & ends, with a few lines cut out in the middle (see above). Those cut-out lines represent the new flavor text, which has switched from 2E's "Outer Plane Intelligence" trigger to the new "Lesser-Intermediate-Greater Deity" descriptions, and thus has fewer categories in that pre-existing system for gods (which I think I prefer). Also, the result for failure on this check has been "safety-bumpered" to simply reduce Int & Cha to 8, and thereby losing spellcasting abilities temporarily (which seems less harsh, but less interesting, than cosmic insanity). But Tweet cuts out Cook's 2E one-automatic-answer charity, here specifying that "no answer is received" in the case of a failed check.

If we just strip out the probabilities for a "True Answer" at each level (neglecting the possibility of accidental truthfulness from the last column), then we see:

• N=1: 39%, 2: 44%, 3: 49%, 4: 60%, 5: 73%, 6: 88%.

Which again is exactly the same as the 1E/2E probabilities at the levels of "1 removed", 2, 3, 5, 7, and 9+  (see in 1E above, and round off to the nearest percentage). So it's obvious that the resident 3E number-cruncher was indeed carefully looking at the 1E/2E table and doing the same probability calculations I did above, to make those results match up as closely as possible, and with just a single die-roll. We can praise this for close observation and efficiency (one die-roll instead of two), but on the other hand this makes you entirely dependent on the lengthy table (no way to break out the two factors into simple probability formulas; the sources are entirely hidden in the 3E text).

Conclusions

The contact higher plane spell was super-weak, effectively unusable, in OD&D and B/X, largely due to an oversight about how compound probability events work (i.e., they get multiplicatively lower). When the spell changed to contact other plane in 1E, Gygax made those probabilities much more tractable, and they were retained effectively unchanged through 2E and 3E (except for the highly questionable Insanity-boost inserted in 2E). Also: flavor-text changed, from OD&D's planes-that-shall-not-be-named, 1E's steps on the Great Wheel, 2E's Intelligence-based Planescapery, and finally 3E's specific classes of deities.

One thing that I don't see addressed here, for the relative weakness of the spell, is to what extent players are allowed to re-ask the same question over again compare answers. If allowed to do this and apply the mechanic as-written, then players could compare answers and use statistical inference to decode what the truth really is -- even if only contacting the lowest-level option in OD&D where almost all of the answers are false. The most obvious response to this is: keep in mind what the entity said previously and repeat the same answer in all such cases. But players could maybe take one or more steps upward, contact a different entity with the same question, and compare those answers. Insanity-permitting, of course.

So, what do you think about the spell? Is it too weak or strong (pretending, for argument's sake, that options like clerical commune are not available)? Have you seen it used in actual games (I never have), and how did it work? Would it be better to discard the big table (remember, it's the only spell like that in the LBBs) and just present core mechanic dice-rolls in its place? I'm almost surprised that 3E didn't go that route instead (but god forbid 3E actually make something short when it could be long). I might also consider using the actual list of responses from the Magic 8-Ball (link), although that would require a bit more paper at the table, if I don't remember the list outright.

(Footnote: An ODS spreadsheet of my various probability calculations is available here.)