Etherium Cache

Etherium Cache enters the battlefield tapped.
{t}: add {u} to your mana pool.
{u}, {t}: add {u}{u}, {w}{u}, or {u}{b} to your mana
pool. Activate this ability only if you control another artifact.
{w/b}{u}: create a colorless artifact token named Etherium with "This artifact enters the battlefield tapped" and "{t}, Sacrifice this artifact: Add one mana of any color to your mana pool."