I was curious about what the differences are for a True Dragon between using its natural Alternate Form feature vs the Draconic Polymorph spell.
The Alternate Form feature (link to Gold Dragon on SRD) says this:
Alternate Form (Su): A gold dragon can assume any animal or humanoid form of Medium size or smaller as a standard action three times per day. This ability functions as a polymorph spell cast on itself at its caster level, except that the dragon does not regain hit points for changing form and can only assume the form of an animal or humanoid. The dragon can remain in its animal or humanoid form until it chooses to assume a new one or return to its natural form.
The Draconic Polymorph spell description (from the Draconomicon) says this:
As polymorph, except as follows: The assumed form can have no more Hit Dice than you have, to a maximum of 20 Hit Dice. Your Strength and Constitution in the new form are above the average for the race or species into which you transform; your Strength is the average for the creature +8, and your Constitution is the average for the creature +2.
So, I have a question about this:
Damage: Does a dragon using the Alternate Form feature only revert to its true form if it takes enough damage to kill said true form, or might it revert to true form if it takes enough damage to kill its assumed form?