Mass Polymorph

I like the ingenuity, is this your design or did you netdeck?

For only having 3 beaters, I think you've made an expert decision. While the Leviathan prevents your other creatures from attacking, if the Leviathan would be removed (easy enough to do, but with Iona the odds are against the opp.) you've got two other solid beaters to follow.

The only downfall is that you're relying on polymorph for the deck to reach its full potential. You could theoretically hard-cast anything in here, but by the time you do so, any competent opponent would have already beaten you. Any solid aggro deck will bring you precariously close to defeat before you can do anything worthy of mention. But I guess that's just the nature of polymorph decks, eh?

Only thing I could suggest to make this better is either a set of Nest Invaders (Two for one polymorph, two chump blockers, and a mana source) or Augury Owl (Scry to prevent useless topdecking, and a chump blocker that prevents flying damage).

I understand the necessity of minimizing your creature count, but I feel either these two cards would benefit you more than hinder you, and with your token generation you would usually morph right through anything lingering in your deck.

Thanks for the input; I can understand exactly where you're coming from due to the times I have played the deck against single or multiple opponents. I normally didn't have a problem in 3+ person games, but 1v1 all comes down to my ability to hold my opponent off until turn 4 or 5; I tend to get Garruk out on turn 4 and use his ability to keep enough mana open to be able to counter spells before my next turn. but other than that I would need a heavier defense until I can use Mass Polymorph.

I would most likely go towards the Augury Owls because I have had times where topdecking has made it close to impossible to get my polymorph off correctly, but the See Beyonds have help in those occasions as well.

How many Augury Owls would you recommend? What should I replace?

I forgot to mention, I looked at a few friends' builds for the deck along with having the idea for Stormtide Leviathan instead of Ulamog or anything else.

Not entirely sure what you'd want to replace. IMO, I think Preordain is better than See Beyond, though both have their merits. You could replace the lesser of the two with the Owl, as it's purpose is to filter through the deck as well as provide a chump blocker. (And push come to shove, if there's nothing else worth targeting you could bounce is with Into the Roil. Not usually the best decision, but an option most players overlook)

Another card that might be worth looking into is Selective Memory. No idea why I didn't think to mention that before..

Kool, thanks for the advice, the third Jace Beleren was actually not supposed to be in there (Because it replaced Ulamog) so I removed one of those and a Roil for two Augury Owls, works great. I have a few Selective Memory(s) so I think I will play around with that too.