Omnath, Locus of Creation
{R}{G}{W}{U}Legendary Creature — Elemental
When Omnath enters, draw a card. 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, Omnath deals 4 damage to each opponent and each planeswalker you don't control.