Mana Screw

When a permanent is tapped for mana, instead it produces one mana of any color it would not normally produce.
Permanents that tap for mana gain {1}{t} : add {c} to your mana pool. (Because
of Mana Screw's effect, that permanent
would instead produce any mana but colorless, or in other words, any color)
{t}: Add {c} to your mana pool.