Journey of Doom

Choose a creature an opponent controls. It gains
trample, and it's controller must attack you or a
planeswalker you control with it this turn if able.
At the end of the next attack step, the chosen
creature gets -X/-X, where X is the total amount
of combat damage it dealt. It's controller loses X
life. Then, for each creature and/or planeswalker
you control that the chosen creature killed, it's
controller discards three cards. If the chosen
creature also dealt combat damage to you this