The assumed form's size can be anything from Fine to Colossal. -- Skip Williamsstrongbow said:Remember that Polymorph references Alter Self, which states that the form you assume may be no bigger than one size of your normal form. So no polymorphing into a hydra unless your normal form is large. sorry man.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.