Ob Nixilis, the Fallen
Legendary Creature — Demon
Landfall — Whenever a land you control enters, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis.
His spark lost, he plots revenge upon the plane whose corrupting mana fractured his soul.
Illustrated by
Tarkir: Dragonstorm Commander#192MythicEnglishLegality
Rulings
A landfall ability triggers whenever a land you control enters 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.
A landfall ability doesn't trigger if a permanent already on the battlefield becomes a land.
Whenever a land you control enters, 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 (As a result, you can have those abilities resolve in the order of your choosing.).