Meria's Outrider
Creature — Elf Archer
Reach
Domain — When this creature enters, it deals damage to each opponent equal to the number of basic land types among lands you control.
Arrows fashioned from the living wood of Yavimaya carry all of the forest's rage in their fire-hardened points.
Lius Lasahido
The List (PLST)
• #DMU-138Rulings
The basic land types are Plains, Island, Swamp, Mountain, and Forest. Land types other than basic land types (such as Desert) don’t contribute to domain abilities.
(wotc • 2022-09-09)
Domain abilities count the number of basic land types among lands you control, not how many lands you control or how many of any type.
(wotc • 2022-09-09)
Rulings
The basic land types are Plains, Island, Swamp, Mountain, and Forest. Land types other than basic land types (such as Desert) don’t contribute to domain abilities.
(wotc • 2022-09-09)
Domain abilities count the number of basic land types among lands you control, not how many lands you control or how many of any type.
(wotc • 2022-09-09)