So, out of the reeking pile of poo that I called my card pool at the prerelease, I came up with these cards as potentials for my 5-color.

Emrakul, the Aeons Torn
Ancient Stirrings (digs for land, artifacts, and colorless spells)
Evolving Wilds
Dreamstone Hedron (too expensive?)
Lone Missionary (too little?)
Wall of Omens
Splinter Twin (this is silly with comes into play effects, but I don't run Kiki Jiki which is usually better).

Everyone should also congratulate Aaron on his top 4 in the prerelease!