Monstrous illusion

Monstrous illusion was a divine magic spell available to mistcallers (specialty priests of Leira, the Mother of Illusionists) and perhaps other priests with an affinity for necromancy or the martial aspect of faith in the form of combat.

Effects
This spell formed a solid illusion around the caster that provided partial protection from harm and bequeathed some of the abilities of the creature chosen, but with restrictions. Restrictions included: Monstrous illusion lasted for at least seven minutes (longer for more experienced casters) or until the caster dropped the illusion, whichever came first. While the spell was active, the caster operated the illusion from the inside and could use any non-magical powers and abilities of the chosen creature except the ability to fly (if applicable). In combat, the caster fought as the chosen creature but was only half as effective as the real thing. Likewise, any damage the illusory creature incurred was reduced by half.
 * The caster must have seen the chosen creature alive and awake sometime in the past.
 * The chosen creature had to be native to Faerûn and not connected to another plane of existence. This eliminated most undead creatures because of the connection to the Negative Energy plane, and creatures like phase spiders with a connection to the Ethereal plane.
 * The chosen creature could not be an individual, like a king, or a unique creature, like the tarrasque.
 * The chosen creature had to be physically large enough to fully encase the caster's body. A large bear worked for most medium-sized casters, but a badger was too small.

Components
This spell required only verbal and somatic components to cast.