Omnath. Locus of Slivers

When Omnath, Locus of Slivers enters, draw a card.

Slivers you control have "Landfall—Whenever a land you control enters, you gain 4 life if this is the first time this ability has resolved this turn. If it's the second time, add {r}{g}{w}{u}. If it's the third time, deal four damage to each opponent and each planeswalker you don't control.