Must the body remain on the Material Plane during astral projection?

Question

The spell 9th-level Sor/Wiz spell astral projection [necro] (PH 201) is one of those high-level legacy spells dating back to at least Advanced Dungeons and Dragons (1978), likely included in Dungeons and Dragons, 3rd Edition and its offspring with the understanding that no one would ever actually use it. Nonetheless, let's say a creature does use an effect like the spell astral projection--for the sake of argument, a demilich, who can use such an effect will as a spell-like ability.

The spell says

By freeing your spirit from your physical body, this spell allows you to project an astral body onto another plane altogether.

You can bring the astral forms of other willing creatures with you, provided that these subjects are linked in a circle with you at the time of the casting. These fellow travelers are dependent upon you and must accompany you at all times. If something happens to you during the journey, your companions are stranded wherever you left them.

You project your astral self onto the Astral Plane, leaving your physical body behind on the Material Plane in a state of suspended animation. The spell projects an astral copy of you and all you wear or carry onto the Astral Plane. Since the Astral Plane touches upon other planes, you can travel astrally to any of these other planes as you will. To enter one, you leave the Astral Plane, forming a new physical body (and equipment) on the plane of existence you have chosen to enter.

While you are on the Astral Plane, your astral body is connected at all times to your physical body by a silvery cord. If the cord is broken, you are killed, astrally and physically. Luckily, very few things can destroy a silver cord. When a second body is formed on a different plane, the incorporeal silvery cord remains invisibly attached to the new body. If the second body or the astral form is slain, the cord simply returns to your body where it rests on the Material Plane, thereby reviving it from its state of suspended animation. Although astral projections are able to function on the Astral Plane, their actions affect only creatures existing on the Astral Plane; a physical body must be materialized on other planes.

You and your companions may travel through the Astral Plane indefinitely. Your bodies simply wait behind in a state of suspended animation until you choose to return your spirits to them. The spell lasts until you desire to end it, or until it is terminated by some outside means, such as dispel magic cast upon either the physical body or the astral form, the breaking of the silver cord, or the destruction of your body back on the Material Plane (which kills you).

Assuming the demilich's extraordinary ability magic immunity allows it even to use its spell-like ability astral projection on itself,¹ can the demilich use its astral projection ability only while on the Material Plane and its (remaining) body (part) can't be moved from the Material Plane without ending the astral projection effect, or is the Material Plane used in the spell description a placeholder for whatever plane the demilich is on when he employs his astral projection ability?

(If it makes a difference, the Pathfinder spell lesser astral projection assumes the latter, although its astral projection spell is identical to the above.)

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¹ Whether a demilich can use its spell-like ability astral projection is its own question here.

Answer 1

Yes, you can use astral projection from planes other than the Material Plane. The Manual of the Planes describes how spells that access transitive planes such as the Astral Plane function on other planes in the section "Moving Among Transitive Planes" (starting on page 45).

Characters generally must use spells or spell-like abilities to access a Transitive Plane. ... the astral projection spell takes you to the Astral Plane ... Such spells should function in any location coexistent with or coterminous to the plane.

It includes various examples of travel between transitive planes on page 46. These examples reinforce that "Material Plane" is a placeholder and that you can use astral projection from anywhere that is connected to the astral plane. Your body will be left behind on the plane you project from.

From the Ethereal Plane to the Astral Plane: You can move to the Astral Plane from almost everywhere on the Ethereal Plane, because the Astral Plane connects to everywhere on the Ethereal Plane. ... If you're using an astral projection spell, your physical body remains in the Ethereal Plane ...

From the Plane of Shadow to the Astral Plane: From the Plane of Shadow, you can use the astral projection spell, leaving your body behind on that plane ...

Answer 2

I think the answer to this depends on the setting you have chosen.

http://forgottenrealms.wikia.com/wiki/Astral_Plane

Describes that "The ramification of [the fact that the Astral Plane overlaps the world tree] is that travel between planes was not easily accomplished without going through the "trunk" of the tree (i.e., the Material plane). Direct connections between separate dominions of the gods was only possible by cooperation between the deities in question."

and that "an Astral traveler had to choose the destination plane before setting out and would only encounter pools that lead to the chosen plane. To change destinations, the traveler had to reenter the Material plane and then begin the journey anew."

So from a world perspective, and assuming you are using Forgotten Realms, the Astral Plane connects every plane to the material plane, but not to each other.

However, this would still leave open the question of using the spell from some other plane, but would limit you to only be able to travel to the Material Plane.

Answer 3

As long as you are on a plane that is touching on the astral plane, the spell should work. There are however very few planes that don't. There is nothing in the rules for planar travel in 3rd edition to indicate that the material plane interacts with other planes in a unique way. In all likelyhood, the spell description simply assumes that you are on the material plane when casting the spell. (Though it's an unreasonably assumption, since plane shift and other planar travel spells become available much earlier.)

Answer 4

Yes, a creature CAN cast Astral Projection from any plane AND their physical bodies CAN move from Plane to plane (just not of their own Volition) while "traveling."

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Note that this spell is different from spells like Blink & Ethereal Jaunt which interact with the Ethereal Plane because only certain planes touch the Ethereal Plane, Material Plane being one of them. However, "all planes are coterminous, to the Astral Plane", therefore, the spell works exactly the same on any plane.

Such spells should function in any location coexistent with or coterminous to the Plane.

As per the spell once they are Astral projected they can't move their physical bodies of their own volition, however, others may guard and move the bodies (or harm them). This includes moving their bodies between planes as long as it requires no conscious or other action from the bodies of the Astral Projected, say through a portal.

Additionally, it's worth pointing out that travelers in the Astral Plane can travel to other planes through "Astral Links" or "Astral Pools". When arriving in the new Plane, a new body is created from the new plane itself. It is identical to its original body but has Immunity to "natural hazards" of the Plane, ie fire from Plane of Fire, negative energy from negative energy Plane, etc..

Using this method to return to the Plane of origin (where u cast the spell from, or your body was moved to by others) is not defined. I'd advise against this method for fear of winding up in a TerminatorTime/Reality loop!

*Important note on source material, PHB is the primary source for players characters and spells etc (which is where this spell is located). However, the DMG is the primary source for Planar issues, while the planar handbook can be used to flesh it out some more. Ofcourse conflicts between the 2 books will result in the DMG "winning" the difference. But this explains why the PHB references Material Plane as it assumes that's where your at and the PHB intentionally doesn't define interactions with other Planes.

Update: This answer has been updated to reflect the updated question.

Note: typed from Phone, please excuse formatting