Hermione, Brightest Witch

Whenever you attack, target attacking creature
becomes Harry and can't be blocked this turn.
It connives. Then choose another attacking
creature with lesser power to become Ron. That creature gains double strike until end of turn.
"Actually, I'm highly logical, which allows me to look
past extraneous detail and perceive clearly that which others overlook."
- Harry Potter and the Deathly Hallows