As beast shape III, except that you change the subject into a Small or smaller animal of no more than 1 HD. A Hellenic Sorceress also has the option to transform the target into a 2 HD animal such as a pig or goat.  If the new form would prove fatal to the creature, such as an aquatic creature not in water, the subject gets a +4 bonus on the save.

If the spell succeeds, the subject must also make a Will save. If this second save fails, the creature loses its extraordinary, supernatural, and spell-like abilities, loses its ability to cast spells (if it had the ability), and gains the alignment and special abilities of its new form in place of its own. It still retains its class and level (or HD), as well as all benefits deriving therefrom (such as base attack bonus, base save bonuses, and hit points). It retains any class features (other than spellcasting) that aren't extraordinary, supernatural, or spell-like abilities.

A Hellenic sorceress can choose to use a special drug in preparation for casting this spell, feeding it to a potential target (either in his food or drink) up to an hour before casting this spell. When used this way, the drug gives the target a -4 penalty to his saving throw against the spell. She can add multiple doses to a common source of food (such as a cooking pot) to drug multiple creatures at once (though each target still requires a separate casting of the spell).

Any polymorph effects on the target are automatically dispelled when a target fails to resist the effects of baleful polymorph, and as long as baleful polymorph remains in effect, the target cannot use other polymorph spells or effects to assume a new form. Incorporeal or gaseous creatures are immune to baleful polymorph, and a creature with the shapechanger subtype can revert to its natural form as a standard action.