This version is as fast as one can imagine. It needs very few lands to make tremendous starts, thanks to Sol Ring. This lone card is such a powerhouse that it has been banned in French PEZ.

Darksteel citadel is there to avoid Stripmine and Sinkhole.

// Lands
4 Darksteel Citadel
4 Seat of the Synod
4 Great Furnace
3 Vault of Whispers

// Creatures
4 Ornithopter
4 Arcbound Worker
4 Disciple of the Vault
3 Atog
4 Frogmite
3 Somber Hoverguard
4 Myr Enforcer

// Spells
4 Cranial Plating
4 Thoughtcast
4 Sol Ring
4 Chromatic Star
3 Chromatic Sphere

// Sideboard
SB: 4 Pyroblast
SB: 3 Red Elemental Blast
SB: 4 Krark-Clan Shaman
SB: 4 Shattering Pulse

Thanks to IdfTrotter for his list.