The Patchwork Boy of Hell Instinct is Amanda's violent and protective nature. She is the primary warrior and has the most strength and vitality. Light, a healer, can cast curative and protective spells. Shadow is a thief-like character with an emphasis on stealth and cunning. He can backstab enemies, manuever around tight spots in the environment, as well as cloak himself in shadow and hide from enemies.
Corruption can cast apocalyptic spells of death and destruction.
Though she defend herself marginally in this state, you'll most likely want to revert to one of the four other personas as quickly as possible. I feel so bad. All characters share a pool of Mana from which spells and shapeshifting are drawn. When Amanda levels up, she can assign points to the various personas to increase their skill. Much like System Shock 2's cybermodule, distributing points lets each player develop his or her own style for playing through the game.