Gnome-Geddon

All permanents are artifacts in addition to their other types. All cards that aren't on the battlefield, spells, and permanents are colorless. Players may spend mana as though it were mana of any color.

Lands you control are Plains. Nonland permanents you control are white. The same is true for spells you control and nonland cards you own that aren't on the battlefield. You may spend white mana as though it were mana of any color. You may spend other mana only as though it were colorless mana.

: If target Plains is tapped for mana, it produces colorless mana instead of white mana. (This effect lasts indefinitely.)

: Target player gains control of target artifact, creature, or land you control.