Can Enlarge Person and Righteous Might stack with Form of the Dragon?

[BlueWitch]

Basically thread title.

Can a person use Form of the Dragon and then get even bigger by casting Enlarge Person or Righteous Might on top of it?

Basically to be as big a dragon as possible.

[Cruiser1]

Can a person use Form of the Dragon and then get even bigger by casting Enlarge Person or Righteous Might on top of it?Enlarge Person no, Righteous Might yes. Form of the Dragon is a polymorph school spell, and so changes your type to Dragon. That means Enlarge Person (http://www.d20srd.org/srd/spells/enlargePerson.htm) (which only works on humanoids) won't work. However, Righteous Might (http://www.d20srd.org/srd/spells/righteousMight.htm) has no such restriction.

Note that Righteous Might says, "Multiple magical effects that increase size do not stack". For example, that means a human can't get larger twice from Enlarge Person and Righteous Might. However, I'd interpret that as still allowing Righteous Might to work on your dragon form, because the polymorph didn't increase your size to the next larger value, but rather just set your size to a particular dimension to begin with.

[Jervis]

Basically thread title.

Can a person use Form of the Dragon and then get even bigger by casting Enlarge Person or Righteous Might on top of it?

Basically to be as big a dragon as possible.

As a side note I recommend using psionic expansion, It’s easier to cheese since it can do more than just 1 category and it is arguably not magical as per RMs rules. Also I think I once got a theory build to colossal ++ with those two spells once

[Gruftzwerg]

Basically thread title.

Can a person use Form of the Dragon and then get even bigger by casting Enlarge Person or Righteous Might on top of it?

Basically to be as big a dragon as possible.

Enlarge Person:
Needs to be cast first, since the "cast" (!) checks for the humanoid type. The effect of the spell can affect any type. So you can later change into a dragon and still profit from the size increase. It's really just a matter of the correct order here.

Stacking Size effects:
While most size increasing effects have a friendly reminder that you can't stack em, the logic behind this term is hidden elsewhere. The problem thrives from the fact that d&d has explicit rules what can stack:

1) Stacking Dmg & Modifiers (see The BASICS (https://www.d20srd.org/srd/theBasics.htm)): We have permission to stack damage (your regular damage calculation while doing dmg) and for "modifiers".
"Modifiers" are defined as a value added or subtracted from a "dice roll"!

2) Stacking Magical Effects (see Casting Spells (https://www.d20srd.org/srd/magicOverview/castingSpells.htm)):

Same Effect More than Once in Different Strengths

In cases when two or more identical spells are operating in the same area or on the same target, but at different strengths, only the best one applies.

Now back to "is size stacking possible?".
In (2) we can see that the same effect (size increase) doesn't stack and only the best one applies. Strict RAW you could argue that you are trying to stack "the same strength" and not "different strength", but this should raise multiple eyebrows if you should attempt this with a real DM. RAI is obvious here. Finally even then, you would still lack the "permission" by RAW to stack it. Since 3.5 already has "stacking rules", you may not fall back to common sense here and have to follow the RAW and show where they say that you have the permission to do so.

Final Conclusion:
Note that "Form of the Dragon" is not a "size changing effect" (even is your character changes in "size" while changing "form"). Thus it works together with either Enlarge Person (if it was cast before FotD) or with Righteous Might.

edit: have a look at "Giant Size" from the Wu-Jen spell list. That spell does what you want.