Omnath, Locus of Creation

Text:

When Omnath, Locus of Creation 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 . If it's the third time, Omnath deals 4 damage to each opponent and each planeswalker you don't control.

Rulings:

• 9/25/2020 Omnath’s landfall ability has no effect each time beyond the third it resolves in a turn.
• 9/25/2020 Omnath’s landfall ability always uses the stack and players may respond to it. It isn’t a mana ability because the event that causes it to trigger isn’t a mana ability, even if it’s the second time the ability has resolved in a turn.
• 9/25/2020 In a Two-Headed Giant game, Omnath’s second ability causes the opposing team to lose 8 life the third time it resolves. Each other player’s planeswalkers—including your teammate’s—are dealt 4 damage.
• 9/25/2020 A landfall ability triggers whenever a land enters the battlefield under your control for any reason. It triggers whenever you play a land, as well as whenever a spell or ability puts a land onto the battlefield under your control.
• 9/25/2020 A landfall ability doesn’t trigger if a permanent already on the battlefield becomes a land.
• 9/25/2020 Whenever a land enters the battlefield under your control, each landfall ability of the permanents you control will trigger. You can put them on the stack in any order. The last ability you put on the stack will be the first one to resolve.