The Pass Possession

You alter your physical form.  

At 50% HP or lower you can change your character sheet-1 (CS-1) to a different character sheet-2 (CS-2) at 50% HP.  When you are using CS-2, YOU can not use magical items to damage creatures with them. But you do gain all magical, racial, and class ability of the character. When CS-2 hit 0 HP you revert back to CS-1 at additional 50% less HP.

The CS-2 can be the same level or 1 higher or lower then CS-1.