Polymorph self

When the polymorph self spell is cast, the spellcaster is able to assume the form of any creature, save those that are noncorporeal. The new form can be as small as a wren to as large as a hippopotamus, as long as it is a creature the caster has seen before. Furthermore, the caster gains its physical mode of locomotion and breathing as well. The spell does not give the new form's other abilities (attack, magic, special movement, etc.), nor does it run the risk of the caster changing personality and mentality.

When the polymorph occurs, the caster's equipment, if any, melds into the new form. The caster retains all mental abilities, including spell use, assuming the new form allows completion of the proper components. The spellcaster can change his form as often as desired for the duration of the spell, and can end the spell at any time. The caster also will return to his own form when slain or when the effect is dispelled.

Note: This version of polymorph self originally appeared in the 2nd Edition Player's Handbook for Advanced Dungeons & Dragons from TSR. Its use here is for the purposes of providing context for the campaign only.