Second look, I think this card could definitely fit in the RG Mana Ramp decks that were so popular at worlds.  Not a bad choice, by any means, at least.

@Midi

Aside from GU Faeries, what deck is running Psi Blast?

@ Shargon...

Can be burned out, but not by any burn spell alone.

I have a Mr P. Blast who would like a wee word with you? ;)

This is a very strong card.  Compare it with a hypothetical 4/4 for 2GG with Shroud (which we can probably all agree would be tier 1):

Colossus pros:  Can be equiped with Warhammer.  Can double it's power, meaning that you can threaten huge amounts of damage without overcommitting to the board.  Can't be chumped by black creatures.  

cons:  Can be burned out, but not by any burn spell alone.  Can be bounced or killed by white spot removal.   

I love this card. 

Problem is, where does it fit?

Gb Elves? Maybe. 

Wg Kithkin? Doubtful

GB GoyfSeize? Doubtful, too expensive.

GBw Doran?  Really?

GW Control (your style deck RoninX)?  Probable.

I guess that it seems like this is a midrange card in a format that has a couple of midrange decks, but is pretty tight on space.

How about that MonoGreen Gauntlet of Power deck? Yes, please.  Just like MaRo.