A deck based on interactions between multicolor cards with some cascade thrown in for lolz.
Comments/suggestions appreciated =)
Rampant Growth is terrible ramp for edh. you do want an Elvish Piper . A Primeval Titan should be here as well. card:Explorer's Scope should be here as well as it says land. Oracle of Mul Daya will help as well.
For fun times, have you considered the Sanctuary cycle from Apocalypse?
Could be cool. Also, the familiars from Invasion block:Nightscape Familiar ,Stormscape Familiar ,Sunscape Familiar ,Thornscape Familiar ,Thunderscape Familiar .They'll at least give you some early play beyond the mana dorks.