Deck In Development (Casual MTG), Ideas?

A really good card for this deck would be Enduring Renewal which when a creature goes to the graveyard from play it comes back to your hand.

Yeah, I foresee a problem. First of all, all of your cards, with myr propagator and myr matrix excluded (they're crap token makers anyways), you have no token production. The tokens are what make mass polymorph completely insane, because if you cast it on turn six after having an awakening zone out from turn three, that's three creatures. From one card. And you don't even have to risk flipping it on your polymorph. A blue/green mass polymorph is usually the best with cards like kozilek's predator and nest invader too. Anyways, you also have a relatively low quality of creatures. Guard gomazowa? Myr propagator? Darksteel sentinel? Yeah you have 5 good targets, but 12 bad ones will just ruin the deck completely. You want decent targets like bogardan hellkite, ulamog, the infinite gyre, and Emrakul. An average opponent can get rid of two guard gomazowas and race the remaining inkwell leviathan. An average opponent will just concede to an eldrazi, though. Anyways, this is the decklist I'd suggest: 4 terramorphic expanse 4 evolving wilds 4 forest 8 island 4 Kahlni garden 4 mass polymorph 4 preordain 4 see beyond 4 negate 4 deprive 1 emrakul, the aeons torn 1 ulamog, the infinite gyre 1 iona, shield of emeria 3 terastodon 4 growth spasm 4 kozilek's predator 2 into the roil This is a standard decklist too, so if you want to make it more casual, add more ponders and progeniti and such.

I would add Armadillo Cloak - gives the enchanted creature +2/+2 and lifelink. Also, Shield of the Oversoul:

As long as enchanted creature is green, it gets +1/+1 and is indestructible. (Lethal damage and effects that say "destroy" don't destroy it. If its toughness is 0 or less, it's still put into its owner's graveyard.)

As long as enchanted creature is white, it gets +1/+1 and has flying.

I also use Heroes; Reunion, which gives hyou 7 life for GW as an instant. Can pump up your Ageless Entity by 7. I would throw some card draw in there, and ways to find a specific creature and also Safewright Quest, which lets you get a forest or plains and put it into play. Good for mana fixing and thinning out the deck.

I have this deck and I have had ridiculously big creatures... with lifelinking, trample, flying and indestructibility...