nimander

it is colossi, btw

also, see beyond is necessary for when you end up drawing the eldrazi or colossi

I love mass polymorph decks, and this one is similar to mine.
A few suggestions from experience: Since these decks have no other win con, you need to mass polymorph as fast as possible, and explore is faster ramp than harrow or cultivate and it gives you a draw. Myr Turbine is too expensive, if you cast it the turn you have 5 mana, and then next turn mass polymorph, it'll have only given you two tokens, spawn generators like nest invader or brood birthing (if you want to splash red) are way more efficient, and give you mana.
Take a look at mine, it goes off between turn 4 and 6 pretty much every time:
http://www.mtgvault.com/ViewDeck.aspx?DeckID=118465

I think that Paradox Haze would work quite well with some of the cards in this deck, and Forced Fruition would help in milling your opp. out, and High Tide for some mana accel.
And Donate is always good for some shenanigans, for example donating Mindmoil to your opp. or donating Forced Fruition to your opp. then you'll be drawing like mad and it would only take a few spells to kill your opp. with general damage; i have a Mindmoil deck that has some parallels to this, if you wnt to check it out, and if you would take a look at my EDH deck, that would be great

Mindmoil Deck: http://www.mtgvault.com/ViewDeck.aspx?DeckID=160708
EDH: http://www.mtgvault.com/ViewDeck.aspx?DeckID=174539

along the same line as slightlyless, here is my mono-green EDH deck, please take a look

http://www.mtgvault.com/ViewDeck.aspx?DeckID=174539

a few suggestions from experience:
Wirewood Guardian, green EDH suffers from a lack of card draw, this helps especially when combo's with rampaging baloths and...

Crucible of Worlds, awesome card, lots of edh decks have land destructions, and works really well with...

Terramorphic expanse and Evolving wilds, deck thinning and comboing capabilities

Also, Azusa could work in this deck, and for more ramp you want Kodama's Reach and Search for Tomorrow

And Tooth and Nail is always awesome, and should definitely be in this deck

"Instants and leveling can be done at any time without leylines." If you read the reminder text you'll not that levelling is not instant speen, but can only be done as a sorcery

rather than coat of arms, try door of destiny, it won't benefit your opponents

do you realize that ensnaring bridge stops your creatures from attacking as well?

the mindsculptor and brainstorm are bit expensive for my tastes; but little Jace would make a good addition as a draw engine and a "destroy target Jace, the Mind Sculptor"

if there are any better, high-cmc red cards then please let me know, red is not really my fave colour

Reliquary Tower is better, it is less vulnerable to destruction, and provides mana

Thanks, high tide and the medallion are really useful, I also added leyline of anticipation: it's even better if I can cast Eternal Dominion on my opp. turn

Oh! I guess I missed that, never mind then, that would work, my mistake

the problem with aether vial is that you have no way of keeping the charge counters from building up, and you can only put creatures into play with the exact cmc of the no. of charge counters on it. I suppose if you put it into play the turn before you board-sweep, then you'll be able to use it, but only then. However, I'm not really sure if there is a suitable replacement, maybe everflowing chalace, if you find yourself with extra mana at the end of your turn. You might also want to sideboard vines of vastwood in case people use exile effects or condemn on your vengevines

it might just be me, but i think that aether vial is a bit slow for this deck, the highest creature cmc you'll be paying is 2 for the fauna shaman, and it can only really work once, as a first turn drop, and if you have a shaman in your hand two turns later. Also, since fauna shaman is so important to the deck, and though they can fetch each other, having 4 would increase the likelihood of having one in your opening hand.

Other than that it looks brutal, I hate playing against vengevine decks

you make some good points, heavy arbalest is a bit wasteful, and claws of valakut would make spikeshot elder pretty badass..

Good array of vamps, a few cards I find useful in my vamp decks are blade of the bloodchief (it can cet pretty ridiculous fast, and it's cheap) and virulent swipe (can deal that last little bit of damage, and the deathtouch can get rid of really big creatures, when you don't have removal, especially good on a hexmage), also, although it's a bit risky, if you have the vamps out, feast of blood is really good, life-gain, and no colour restrictions, although any mass removal sort of makes it useless, sideboard maybe?

the plague myr rather than vector asp was a good call. I see the arbalests as being a finisher, i equip them to a creature with infect (like the plague myr) and then when I get my opp. to 8 (or 6 if i've got two out) i finish them off.

claws of valakut and the basilisk collar might be good sideboard cards, but atm im trying to keep the cost of this deck down insofar as it's possible

why only 3 of the destructive forces, if you're building the deck around it?