Flameborn Cerberus

Haste, Double Strike
Whenever Flameborn Cerberus attacks, reveal a card at random from your hand. If it's a Mountain, you may put it on the battlefield tapped. Otherwise, exile it.
Whenever a Mountain enters the battlefield, put a 2/2 Red Elemental creature token with haste onto the battlefield.
{r}: Flameborn Cerberus gets +1/+0 until the end of turn.