[3.5] Why don't Enlarge Person and Expansion stack?

[Totema]

There's language at the end of the Enlarge Person description that states "Multiple magical effects that increase size do not stack." But Expansion is not a spell or SLA, it's a manifestation. Psionic, not magic. Is there a looser meaning to "magic" in this case, or am I missing something else?

[Twilightwyrm]

Depends on the level of Psionic/Magic transparency in any given campaign, and how much your DM favors the RAW verses the RAI. If none and RAW, that there is a compelling case that this should stack. Most anything less (anti-magic negating psionics, for instance), and your case becomes quickly less compelling. I'd say that, since Enlarge Person was written before psionics came out, it was most likely not intended to stack with any other similar effect (for pretty apparent balance reasons).

[Kelb_Panthera]

Magic transparency says that, at the effect end, there's really no difference between spell, power, spell-like, and psi-like effects.

To whit:


Stacking Effects

Powers that provide bonuses or penalties on attack rolls, damage rolls, saving throws, and other attributes usually do not stack with themselves. More generally, two bonuses of the same type don’t stack even if they come from different powers, or one from a power and one from a spell. You use whichever bonus gives you the better result.


Same Effect More than Once in Different Strengths

In cases when two or more similar or identical effects are operating in the same area or on the same target, but at different strengths, only the best one applies. If one power or spell is dispelled or its duration runs out, the other power or spell remains in effect (assuming its duration has not yet expired).

Enlarge person and expansion have the same effect and, consequently, only the better of the two applies; usually expansion.

[Chronos]

Expansion is not a spell, but it is a magical effect.

[tyckspoon]

Well, regardless of whether you want to argue about whether 'psionics' is or is not considered 'magic' (it is, btw, for most purposes), they don't stack for a much simpler reason: Expansion itself forbids it. It has this rider-


Multiple effects that increase size do not stack, which means (among other things) that you can’t use a second manifestation of this power to further expand yourself.

Which you'll notice makes no distinction whatsoever about the source of the size-increasing effect. Expansion does not stack with Enlarge Person, Giant Size, the Goliath Barbarian ACF Mountain Rage, or anything else that increases size. And if you take this as a general rule, none of those stack with anything else either.