sweet deck really like some of the combo outs just i would make room for Enter the Infinite and Font of Mythos or Howling Mine might be a good edition for you maybe Jace's Archivist might be better for your purpose of the deck seeing that you are after the combo out in your deck.... i have a similar style i run U/B so i can run so many combos it doesn't mess me up if i lose out on 2-3 b/c the deck abruptly ends and looking at yours i can see it doing the same thing.
Sarkhan Vol is really good in Mayael decks too since he can give haste to all your creatures or steal an unnerving blocker. Seedborn Muse is pretty good too and lets you reactivate Mayael in every players turn.
still, it's for casual play as there aren't any sanctioned events that I can go to it's really a mute point as in casual play I can grab any printed mtg card, the gatherer doesn't even exclude un-cards, and my playgroup just loves the deathwish as laughs usually ensue after.
Also Anax and Cymede is a legendary so a 4 of might me a little excessive. If you draw two that's just not fun. Maybe drop him down to 2-3 drop Obelisk of Urd down to 2-3 and maybe add Spear of Heliod and Hall of Triumph for some additional anthem effects, and minor removal. 1-3 of them depending on how you're feeling
I would add Spearbreaker Behemoth, Sigarda, Host of Herons, Angel of Serenity, Balefire Dragon, Engulfing Slagwurm, Garruk's Horde, Moldgraf Monstrosity, Meglonoth, Soul of the Harvest, Novablast Wurm and especially Penumbra Wurm to the suggestion list (even if some of them are hard at your budget limit).
I simply love Penumbra Wurm by the way. Board whipe? Still got a wurm. Don't want it? Spare another card to get rid of it. (2 cards to really get rid of your complete boards sounds perfect to me and still having a 6/6 trampler after a board whipe still sounds perfect)
I hope this helped. Greets MA.
I'm not sure about that Arc Lightning I get what you're trying to do but you should definitely replace the with Coordinated Assault one less heroic trigger but two less mana, make te deck a little faster. Or you could add Titan's Strength extra scry, or Dragon Mantle mana dump and card draw. Both of those on anax could be some real hurt.If you like my suggestions you should check rw heroic out. I went a different direction and have spent a lot of time on it. Also, Lise a confluence and add a fourth forge, could save a little hurt at least. :)