Karn

Sacrifice a permanent: Return target creature to its owner's hand.

Whenever a creature deals damage to you, destroy it.

If a creature you control would deal damage, it deals double that damage instead.

Spells you cast cost 1 less to cast.

Your opponents play with their hands revealed.

If a basic land you control is tapped for mana, it produces mana of a color of your choice instead of any other type.

Whenever a creature you control deals damage to a creature, destroy the other creature. It can't be regenerated.

Creatures you control have shadow. (They can block and be blocked only by creatures with shadow.)