The Rumbling

I - Each opponent creates a 0/4 colorless Wall artifact creature token with defender and "this creature can't be sacrificed".
II - Each creature you control explores.
III - Destroy all walls. For each wall destroyed this
way, create a tapped 6/6 green Giant creature token.
IV - Giants you control get +2/+2, trample and annihilator 2 until end of turn.