Blood Moon

Enchantment

Nonbasic lands are Mountains.

First printed August 1, 1994 in The Dark

Legality

August 7, 2020
If a nonbasic land has an ability that triggers "when" it enters the battlefield, it will lose that ability before it can trigger.
August 7, 2020
This effect doesn't affect names or supertypes. It won't turn any land into a basic land or remove the legendary supertype from a legendary land, and the lands won't be named "Mountain."
August 7, 2020
Nonbasic lands will lose any other land types and abilities they had. They will gain the land type Mountain and gain the ability "{T}: Add {R}."
August 7, 2020
If a nonbasic land has an ability that causes it to enter the battlefield tapped, it will lose that ability before it can apply. The same is also true of any other abilities that modify how a land enters the battlefield or apply "as" a land enters the battlefield, such as the first ability of Cavern of Souls.