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Magic can cause creatures and characters to change their shapes-sometimes against their will, but usually to gain an advantage. Polymorphed creatures retain their own minds but have new physical forms.
The new form can range in size from Diminutive to one size larger than the subject’s normal form, and can have no more Hit Dice than the subject has, and cannot have more than 15 Hit Dice in any case. Polymorph cannot change the target into constructs, elementals, outsiders or undead unless the target is already one of these types.
If a polymorphed creature dies, it returns to its original form.
When the polymorph occurs, the subject’s equipment, if any, transforms to match the new form. If the new form does not use equipment, the equipment melds into the new form and becomes nonfunctional. Any part of the body or a piece of equipment that is separated from the whole reverts to its original form.
When a creature is polymorphed it regains hit points as if it had rested for a day, though this change does not provide other benefits of rest such as the restoration of lost ability score points. Returning to the target’s normal form does not provide this benefit.
The target of the polymorph gains the physical and natural abilities of the new form. Extraordinary, supernatural, or spell-like abilities are not “natural”. Fast movement speeds (nonflying speeds above 60 feet and flying speeds greater than 120 feet) are usually the result of extraordinary or supernatural abilities; speed in these cases is limited to 60 feet and 120 feet, respectively. Low-light vision is considered a natural ability.
The subject gains scores and abilities that are average for the new form.
The subject retains its Intelligence, Wisdom and Charisma scores, level and classes, hit points (despite any change in Constitution), alignment, base attack bonus and save bonuses (though new Strength, Dexterity and Constitution scores may affect adjusted attack and save bonuses).
The subject retains its original type, extraordinary abilities, spells, and spell-like abilities, but not its supernatural abilities.
Since creatures do not change types, a slaying or bane weapon designed to kill or harm creatures of a specific type affects those creatures even if they are polymorphed. Likewise, a creature polymorphed into the form of a creature of a different type is not subject to slaying and bane effects directed at that type of creature.
A ranger's favored enemy bonus is based on knowing what the foe is, so if a creature that is a ranger's favored enemy polymorphs into another form, the ranger is denied his bonus.
A dwarf's bonus for fighting giants is based on shape and size, so he does not gain a bonus against a giant polymorphed into something else, but does gain the bonus against any creature polymorphed into a giant.