Radha, Coalition Warlord
Legendary Creature — Elf Warrior
Domain — Whenever Radha becomes tapped, another target creature you control gets +X/+X until end of turn, where X is the number of basic land types among lands you control.
Carly Mazur
Dominaria United (DMU)
• #351Rulings
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)