Prismatic Omen

Oracle Text

Lands you control are every basic land type in addition to their other types.

Card Rulings

5/1/2008 Each land you control will have the land types Plains, Island, Swamp, Mountain, and Forest. They’ll also have the mana ability of each basic land type (for example, Forests can tap to produce ). They’ll still have their other subtypes and abilities.
5/1/2008 Giving a land extra basic land types doesn’t change its name or whether it’s legendary or basic.