Kiyoko, the Shadow Moth

Ninjutsu {2}{u}{b} ({2}{u}{b}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)

Ninjas you control get +1/+1 as long as an opponent
has three or fewer cards in hand.

Whenever Kiyoko, the Shadow Moth deals combat
damage to a player, that player's maximum hand
size is reduced by four until your next turn.