Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Target creature gets -2/-2 until end of turn.

Flying, trample
Ward—Discard a card.
Creatures your opponents control have base toughness 1.

Destroy target creature or enchantment. You lose 2 life.

Black spells you cast cost {1} less to cast.