Aang, Elemental Avatar

When Aang, Elemental Avatar enters the battlefield, draw a card.
Landfall —Whenever a land enters the
battlefield under your control, 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, Aang deals 4 damage
to each opponent and each planeswalker you
don't control.