Shantu, Realm's Conquest

Flying, haste
At the beginning of your upkeep, you may take 5 damage. If you don't, transform Shantu Realm's Conquest. Player's can't gain life.
Pay {x}: You may cast all red instants with a
converted mana cost of X from your hand this
turn without paying their mana cost. They can't
be countered. Take 3 damage for each spell casted
this way.