This deck is scary..and scary awesome...I'm not sure if my knowledge could improve upon it. So instead I'll just +1 and stand back to admire.

If you have have Orim's Chant then Isochron Sceptor is a must. You have your choice of locking someone out with it, or saving yourself. It's easy control and protection and the best part is either one is still usable without the other.

Also Spellbreaker Behemoth

I run Lurking Predators in my Mayael EDH: Mayael's Big Stompy Beasts. The hate it draws it staggering.

Mayael's best friend is Sensei's Divining Top , letting you see what creatures Mayael will hook. It also synergises well with Lurking Predators

really? no Worldspine Wurm ?

TwistedMoonlight I don't have Worldspine Wurm because honestly, I don't think there's much I could take out. I'm trying to figure out how to work in Lurking Predators (Thanks TrevHulkC but even that is a problem. The only creature I could think to take out would be Yavimaya Elder , but he's a great mana balancer and I get to draw a card. I like Sensei's Divining Top , but Mirri's Guile and Sylvan Library accomplish nearly the same thing. I'll continue to consider worldspire wurm though, because he's a super fatty. Same goes for Lurking Predators , although that's got priority at this point. Thanks for the suggestions guys!

In terms of removals/replacements, my suggestions are:

Lurking Predators for Wild Pair . Same CMC/type, so it won't mess with curve or balance. Predators will trigger far more often though, as well as controlling opponents effectively. Pair lets you double up on the 6/6s you have, but it also relies on you playing it from hand; which Mayael doesn't do. Predators also works better with Mirri's Guile and Sylvan Library .

I think Worldspine Wurm replaces Avenger of Zendikar . I don't think he does much to improve this deck. He needs more Plant tribal to really get going.