Yiveila, Seru Beastcaller

Instinct (When this creature attacks, discard a card
at random. This creature gets +X/+X until end of
turn, where X is the discarded card's converted
mana cost.)
Creatures you control have haste.
Whenever another creature you control attacks,
return target card from your graveyard to your
hand. If you can't, draw a card.