Rainbow Vale

{t}: Add one mana of any color. An opponent
gains control of Rainbow Vale at the beginning
of the next end step.
"The Rainbow Vale is the only place form which Cu
Cul Cairn Éire can be contacted. Unrestful, it's
location wanders Tyr Ober’Nog. It is never in the
place last found, and those who seek it must wait on
fortune for find it again."