Child of Alara

Trample
When Child of Alara dies, destroy all nonland permanents. They can't be regenerated.

Voidslime

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Leyline of the Void

If Leyline of the Void is in your opening hand, you may begin the game with it on the battlefield.
If a card would be put into an opponent's graveyard from anywhere, exile it instead.

Void Mirror

Whenever a player casts a spell, if no colored mana was spent to cast it, counter that spell.