Does Prismatic Omen make it so that I can tap land for any type of mana, or does it only change the effects of spells like Corrupt?
* 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 :g. They'll still have their other subtypes and abilities.
No, I am not a judge. That's why I like to quote sources such as the rules that trump judges.