Original D&D
Projected Image: By means of this spell the Magic-User projects an image of himself up to 24" away, and all spells and the like used thereafter appear to originate from the Projected Image. Duration: 6 turns. Range: 24".
Here's projected image, as it appears in OD&D; it make an illusory duplicate of the caster, from which his or her spells now originate. Reading this, I would raise a few questions: If you see a separate duplicate of a caster (not close-by as for mirror image), don't you have proof that the one casting spells is the illusory one? The long range of of 24" is very nice but can the caster control it from out-of-sight (around a corner, through a screen or door, behind numerous stone walls? Does the caster get some kind of sensory report to permit that long-distance functioning? And is this really worth a 6th-level (top) slot?
The Swords & Spells specification is no different (Range: 24", Area Effect: personal, Turn Duration: 6), so with that we'll move on to the Moldvay/Cook rules.
Expert D&D
Projected Image
Range: 240'
Duration: 6 turns
This spell creates an image of the magic-user that cannot be distinguished from the original except by touch. All spells cast by the magic-user will seem to come from the image. However, the caster must still be able to see the target. If touched or struck by a melee weapon, the image will disappear. Spells and missile attacks will seem to have no effect on the image. The magic-user who casts the spell can make the image appear up to 240' away.
Cook keeps the name & basics the same, but inserts some answers to those rather obvious, and continually nagging, questions about illusions. The caster must see the target of any spell normally (but not the projected image?). The illusion disappears if touched physically, but is immune to spells and missiles (very similar to other Cook-interpreted illusions such as phantasmal force). And spells still come from the image, no exceptions.
AD&D 1st Edition
Project Image (Alteration, Illusion/Phantasm)
Level: 6
Range: 1"/level
Duration: 1 round/level
Area of Effect: Special
Components: V, S, M
Casting Time: 6 segments
Saving Throw: None
Explanation/Description: By means of this spell, the magic-user creates a non-material duplicate of himself or herself, projecting it to any spot within spell range which is desired. This image performs actions identical to the magic-user -- walking, speaking, spell-costing -- as the magic-user determines. A special channel exists between the image of the magic-user and the actual magic-user, so spells cast actually originate from the image. The image can be dispelled only by means of a dispel magic spell (or upon command from the spell caster), and attacks do not affect it. The image must be within view of the magic-user projecting it at all times, and if his or her sight is obstructed, the spell is broken. The material component of this spell is a small replica (doll) of the magic-user.
Here's Gygax revision (and renaming) of the spell in AD&D. The range is now variable with level (as usual), and the duration is now in 1-minute rounds (as happened to most spells in turns from OD&D Vol-1, prior to the turn = 10 minutes stipulation that appeared in Vol-3). Notice that his answers to the questions from OD&D are the converse of Cook's: the caster must maintain line-of-sight to the projected image, but apparently not the targets of any spells coming from it. No normal attacks of any sort affect it or can banish it (even melee), which is somewhat in line with Gygax's more powerful interpretation of phantasmal force (which stays in the game as long as the caster makes it respond to attacks in a realistic manner). Note that we still have all spells automatically coming from the projected image, which to me maintains the obviousness of identifying which is image and which is real caster (unless the caster always manages to be screened or in some hidey-hole; perhaps best used for audiences in their personal stronghold?).
Project image is not among the spells with errata notes in the 1E DMG.
AD&D 2nd Edition
Project Image
(Alteration, Illusion/Phantasm)
Range: 10 yds./level
Duration: 1 rd./level
Area of Effect: Special
Components: V, S, M
Casting Time: 6
Saving Throw: None
By means of this spell, the wizard creates a nonmaterial duplicate of himself, projecting it to any spot within spell range. This image performs actions decided by the wizard -- walking, speaking, spellcasting -- conforming to the actual actions of the wizard unless he concentrates on making it act differently (in which case the wizard is limited to half movement and no attacks).
The image can be dispelled only by means of a successful dispel magic spell (or upon command from the spellcaster); attacks pass harmlessly through it. The image must be within view of the wizard projecting it at all times, and if his sight is obstructed, the spell is broken. Note that if the wizard is invisible at the time the spell is cast, the image is also invisible until the caster's invisibility ends, though the wizard must still be able to see the image (by means of a detect invisibility spell or other method) to maintain the spell. If the wizard uses dimension door, teleport, plane shift, or a similar spell that breaks his line of vision, the project image spell ends.
The material component of this spell is a small replica (doll) of the wizard.
Cook's second take at the project image spell shares most of the rules that Gygax laid down in 1E -- such as the requirement that the caster remain in sight of the image (not targets of the spell). What I am not found of here is the added detail on what happens if the caster is invisible (presumably something a player of Cook's once did), and cessation of the spell in case of the wizard teleporting (which is really implied by the line-of-sight rule) -- both seem like unnecessary complications that will rarely happen, things the DM should be able to adjudicate, and making the spell text bloated and somewhat harder to read.
D&D 3rd Edition
Project Image
Illusion (Shadow)
Level: Brd 6, Sor/Wiz 6
Components: V, S, M
Casting Time: 1 action
Range: Medium (100 ft. + 10 ft./level)
Effect: One shadow duplicate
Duration: 1 round/level (D)
Saving Throw: Will disbelief (if interacted with)
Spell Resistance: No
The character creates a shadow duplicate of him or herself; it looks, sounds, and smells like the character but is intangible. The shadow mimics the character's actions (including speech) unless the character concentrate on making it act differently. The character can see through its eyes and hear through its ears as if the character were standing where it is, and during the character's turn in a round the character can switch from seeing through its eyes to seeing normally, or back again. If the character desires, any spell the character casts whose range is touch or greater can originate from the shadow instead of from the character. (The shadow is quasi-real, just real enough to cast spells that the character originates.) The shadow can cast spells on itself only if those spells affect shadows. The character must maintain line of effect to the shadow at all times. If the character's line of effect is obstructed, the spell ends. If the character uses a spell that breaks the character's line of effect, even momentarily, the spell ends.
The 3rd Edition designers make some subtle, but I think in effect fairly powerful, changes. (If you scan the spell quickly it might be easy to miss what they did here.) First, while the caster must maintain "line of effect" to the image, the caster is given full sensory input from the perspective of the image -- which nicely rationalizes why throughout the AD&D line you don't need line-of-sight to targets of the spells (because you can just see out from the image itself). Second, spells originating from the image are now optional to the caster -- which I think is great, because now you have a legitimate way of masking which is which, even if both are in plain sight on the battlefield or dungeon, say (in addition to still being able to cast those protections and escape spells on the actual caster himself, if desired). Also that junky language specific to invisibility and teleports is cleaned out. I think this is a really good job, which is characteristic of why I do respect much of what the 3E designers were doing.
Conclusions
Basically, I like what the 3E writers did enough -- answering my lingering questions from the days of OD&D, making the spell rather more powerful to legitimize it's 6th-level status -- that I mostly kept the language we received through the SRD, with minor trimmings. Here it is as presented in my Book of Spells, 2nd Edition:Project Image: (Range: 24 inches, Duration: 6 turns) The caster creates an illusory image of him or herself; it looks, sounds, and smells like the caster but is intangible. The illusion mimics the caster's actions (including speech) unless the caster concentrates on making it act differently. If the caster desires, any spell from the caster whose range is touch or greater can originate from the image instead of from the caster. Attacks do not affect it, and it does not disappear when touched.
I keep the optional status of spells originating from the illusion, which I think is a great idea. I actually cut out the language specifying getting sensory input from the image, not because I loathe it, but simply because it would make the text for spell longer than anything else in the book; and the line-of-effect requirement is by implication with all other spells (both intentionally subject to DM adjudication). I keep the AD&D sensibility of the image not being subject to any attacks (thus making it stronger than phantasmal force which does disappear with any melee hit, as in OD&D).
Is it now worth the 6th-level slot? In what circumstances do you think this spell would most commonly get used? Do you agree with the 3E-era optional image-spellcasting allowance?