Ennia, Hall of Frozen Gold

{t}: Add {c}.
{2}, {t}: Create a colorless Treasure artifact token with "{t}, Sacrifice this artifact: Add one mana of any color."
Sacrifice six Treasures, {t}: Tap up to four target creatures. Those creatures don't untap during their controller's next untap step.
A cave lying in a glacier that shimmers with the gold of countless ages.