Omnath, lord of elements

landfall—whenever a land enter the battlefield
under your control:
plains: gain 1 life.
island: draw a card then discard a card.
swamp: exile one card from opponents graveyards.
mountain: omnath, lord of elements deal 1 damage
to each opponents.
forest: create a 2/2 green elemental token.
omanth, leader of the primordial elements, unleashes
his power in response to threats