Fist of Suns

Oracle Text

You may pay WUBRG rather than pay the mana cost for spells that you cast.

Card Rulings

12/1/2004 This is an alternative cost to cast a spell.
12/1/2004 You can't pay more than one alternative cost for a spell. For example, you can't cast a spell using its flashback ability by paying {W}{U}{B}{R}{G}. Likewise, you can't pay {W}{U}{B}{R}{G} to cast a creature with morph face down.
12/1/2004 Note that combining this card with Mycosynth Lattice from the Darksteel set means that all spells can be cast for five mana of any type (colored or colorless).
2/1/2014 If you pay {W}{U}{B}{R}{G} rather than pay the mana cost of a spell with {X} in its mana cost, the only legal choice for X is 0.