One With Ixalan

Into the Fray - If you control a commander, at the beginning of your upkeep create a 0/1 green egg creature token with defender.
{2}, Sacrifice an egg: Search your library or
graveyard for a dinosaur creature card, reveal it,
and put it into your hand. Until the beginning
of your next end step, spells with the revealed
card's name cost {2} less to cast and gain haste.