Xyru Specter

Flying
Whenever Xyru Specter deals damage to an opponent, that player discards a card unless they challenge you. If challenged, and you show them two black cards in your hand, they must discard two cards.

Sliv-Mizzet, Hivemind

Slivers you control have flying and “Whenever you draw a card, this creature deals 1 damage to any target” and “: Draw a card.”