Don't want to go the obvious Storm route? Aluren for infinite colorless. Could make for a nice R/G Hydra deck...

Turn 1: Forest, Sol Ring
Turn 2: Forest, Aluren
Turn 3: Mountain, free Grinning Ignus, infinitely huge scary hydra of your choice, free Hellraiser Goblin for Haste, and then Rancor for Trample. Proceed to beat face.

Sure, it needs 9 cards in 3 turns, but it's fun to dream!