Cerulea, the Anchored Capital

When Cerulea, the Anchored Capital enters the
battlefield, tap 3 untapped lands you control.
Those lands can not be untapped while Cerulea,
the Anchored Capital is on the battlefield.
{t}: Add {2}. For each land that is tapped due to
Cerulea, the Anchored Capital, add one mana of
any color that could be produced by that land.
Sacrifice Cerulea, the Anchored Capital, if there
are no tapped lands on the battlefield.