Here is what i personally would cut: Akroma, Angel of Wrath- She's just a big dumb creature, which is cool, but I prefer my EDH creatures to do more. Thundermaw Hellkite - See above Borborygmos Enraged - I played him in my list for a long time, he always under preformed. I never have lands in hand, even when i added every bounceland in my colors. Spellbreaker Behemoth - When Mayael gets going, you don't need to cast spells. Stalking Vengeance - I don't think you need to burn the opponent. Xenagos, God of Revels - I just wasn't ever happy when i played him.
That's the Mayael targets i don't like. I would replace them with: Utvara Hellkite - He can win the game on his own. Scourge of the Throne - Its Aurelia #2, but works with Utvara Hellkite! Inferno Titan - Mayael decks are notorious for not having much removal, but this guy can remove a lot of the utility creatures in the format. Scourge of Kher Ridges - More removal that is also a Mayael target, and works with Utvara Hellkite. Thunderfoot Baloth - Just a better Xenagos, God of Revels if you ask me. Eternal Dragon - I LOVE Mayael targets that don't just sit in your hand when drawn. This guy is mana fixing if drawn. Plus, its a dragon.
Now i would like to recomend changing up your Lands. Here is what i would cut: Tree of Tales, Great Furnace, Ancient Den - I'm not sure why you have the artifact lands, they die to mass artifact removal or turns Naturalize into LD. Razorverge Thicket, Copperline Gorge - Fastlands generally aren't good in EDH, in a 99 card deck it's hard to draw them before turn 4. Battlefield Forge, Karplusan Forest, Brushland - I'm not a big fan of painlands in EDH either.
I would add: Gruul Turf, Selesnya Sanctuary, Boros Garrison, Karoo, Dormant Volcano, Jungle Basin - Bouncelands are awesome. Synergy with Garruk, Voyaging Satyr, Magus of the Candelabra, Krosan Restorer, Weathered Wayfarer, etc. Kessig Wolf Run - Can win you the game when you have stuff like Vorinclex, Voice of Hunger. Jungle Shrine - Taps for all 3 colors.
Now to the ramp: Arbor Elf - I feel like sometimes he wouldn't even tap for mana if you get screwed off forests. Avacyn's Pilgrim - 1 mana 1/1 that taps for only one isn't where you wanna be in EDH. Sakura Tribe Elder - He is fine usually, but i think you can do better. Druid of the Anima - She is just too vanilla for my taste. Farhaven Elf - He is also usually fine, but i think you can do better. Khalni Heart Expedition - Just not a big fan of this one. Darksteel Ingot - I think you can do better. Chromatic Lantern - See above.
I would recommend adding: Sylvan Scrying - It may not go on the field but when you can get a Maze of Ith or Kessig Wolf Run it's worth it. Weathered Wayfarer - See above. Magus of the Candelabra, Krosan Restorer, Voyaging Satyr - Goes well with the bouncelands if you decide to go that route. They also go nicely with Maze of Ith and High Market etc. Bloom Tender - Turn 2 him, turn 3 Mayael, turn 4 activate Mayael. Exploration - Turn 1 exploration, turn 2 Mayael, turn 3 activate Mayael. Harrow - Just an all around good card in EDH.
Tutor and Draw: Harmonize - Usually i like Harmonize but here i think it can be replaced. Green Sun's Zenith - I don't like the restriction of only getting green creatures.
I would add: Eladamri's Call - A better GSZ in my opinion. Greater Good - I take the fact that you're running High Market as you know the power of a sac outlet. Here is one that draws cards!
Miscellaneous: Mimic Vat - I don't think it reaches it's full potential in this deck.
Adding: Swiftfoot Boots - Just another way to protect Mayael.
So those are my suggestions! Sorry if they sounded mean lol hope they were helpful. I tried keeping them budget friendly since i wasn't sure what your opinion was on that (though you are running eldrazi titans...) and i tried trading ramp for ramp, creatures for creatures etc. If you want more help definitely check out the primer on Mayael here on the site, it helped me alot when i was building my Mayael deck.
All the minus 1 minus 1 counters do not remove the plus 1 plus 1 counters. Both counters will exist on that creature, so if you are running the minus 1 minus 1 counters to get extra undying triggers, it won't work. Because the interaction works that way I wouldn't even run any of the minus 1 minus 1 guys, they just don't seem worth it.
Not sure if you intended on redoing the budget list any time soon, but I recommend it, it's not as budget as it used to be lol. Not a huge priority, and it may not even be too much too change, just thought I would mention it.
Ashes to Ashes is probably better, for Gild you pay an extra mana to get to hit anything, which is fine, but you lose a target and get a token, (which I personally don't think is worth it).
Akroma, Angel of Wrath- She's just a big dumb creature, which is cool, but I prefer my EDH creatures to do more.
Thundermaw Hellkite - See above
Borborygmos Enraged - I played him in my list for a long time, he always under preformed. I never have lands in hand, even when i added every bounceland in my colors.
Spellbreaker Behemoth - When Mayael gets going, you don't need to cast spells.
Stalking Vengeance - I don't think you need to burn the opponent.
Xenagos, God of Revels - I just wasn't ever happy when i played him.
That's the Mayael targets i don't like. I would replace them with:
Utvara Hellkite - He can win the game on his own.
Scourge of the Throne - Its Aurelia #2, but works with Utvara Hellkite!
Inferno Titan - Mayael decks are notorious for not having much removal, but this guy can remove a lot of the utility creatures in the format.
Scourge of Kher Ridges - More removal that is also a Mayael target, and works with Utvara Hellkite.
Thunderfoot Baloth - Just a better Xenagos, God of Revels if you ask me.
Eternal Dragon - I LOVE Mayael targets that don't just sit in your hand when drawn. This guy is mana fixing if drawn. Plus, its a dragon.
Now i would like to recomend changing up your Lands. Here is what i would cut:
Tree of Tales, Great Furnace, Ancient Den - I'm not sure why you have the artifact lands, they die to mass artifact removal or turns Naturalize into LD.
Razorverge Thicket, Copperline Gorge - Fastlands generally aren't good in EDH, in a 99 card deck it's hard to draw them before turn 4.
Battlefield Forge, Karplusan Forest, Brushland - I'm not a big fan of painlands in EDH either.
I would add:
Gruul Turf, Selesnya Sanctuary, Boros Garrison, Karoo, Dormant Volcano, Jungle Basin - Bouncelands are awesome. Synergy with Garruk, Voyaging Satyr, Magus of the Candelabra, Krosan Restorer, Weathered Wayfarer, etc.
Kessig Wolf Run - Can win you the game when you have stuff like Vorinclex, Voice of Hunger.
Jungle Shrine - Taps for all 3 colors.
Now to the ramp:
Arbor Elf - I feel like sometimes he wouldn't even tap for mana if you get screwed off forests.
Avacyn's Pilgrim - 1 mana 1/1 that taps for only one isn't where you wanna be in EDH.
Sakura Tribe Elder - He is fine usually, but i think you can do better.
Druid of the Anima - She is just too vanilla for my taste.
Farhaven Elf - He is also usually fine, but i think you can do better.
Khalni Heart Expedition - Just not a big fan of this one.
Darksteel Ingot - I think you can do better.
Chromatic Lantern - See above.
I would recommend adding:
Sylvan Scrying - It may not go on the field but when you can get a Maze of Ith or Kessig Wolf Run it's worth it.
Weathered Wayfarer - See above.
Magus of the Candelabra, Krosan Restorer, Voyaging Satyr - Goes well with the bouncelands if you decide to go that route. They also go nicely with Maze of Ith and High Market etc.
Bloom Tender - Turn 2 him, turn 3 Mayael, turn 4 activate Mayael.
Exploration - Turn 1 exploration, turn 2 Mayael, turn 3 activate Mayael.
Harrow - Just an all around good card in EDH.
Tutor and Draw:
Harmonize - Usually i like Harmonize but here i think it can be replaced.
Green Sun's Zenith - I don't like the restriction of only getting green creatures.
I would add:
Eladamri's Call - A better GSZ in my opinion.
Greater Good - I take the fact that you're running High Market as you know the power of a sac outlet. Here is one that draws cards!
Miscellaneous:
Mimic Vat - I don't think it reaches it's full potential in this deck.
Adding:
Swiftfoot Boots - Just another way to protect Mayael.
So those are my suggestions! Sorry if they sounded mean lol hope they were helpful. I tried keeping them budget friendly since i wasn't sure what your opinion was on that (though you are running eldrazi titans...) and i tried trading ramp for ramp, creatures for creatures etc. If you want more help definitely check out the primer on Mayael here on the site, it helped me alot when i was building my Mayael deck.