Yharon, Dragon of Rebirth

Flying, haste
Whenever you cast a spell from exile, you may have Yharon deal 2 damage to you, if you do, exile the
top card of your library, until the end of your next turn you may play it.

When Yharon enters and at the beginning of your
end step, if your life total is less than or equal to half your starting life total, exile Yharon, then return
it to the battlefield transformed under its owner’s control.