Terrain Generator gets more Swamps into play at low opportunity cost. If you ran more permanents I would also suggest Nykthos, Shrine Nyx. Liliana of the Dark Realms is a great way to search up for Swamps, produce lots of mana and give you more kill with her.
I don't see any Sac Outlets or Bounce to get Maga back into your hand to cast again. Also, since you play a lot of 'all in' spells, perhaps a Boseiju, Who Shelters All?
I think you should consider adding in the cheap draw spells like Night's Whisper, Sign in Blood, and Read the Bones. They give you something to do in the early game, and in the late game if you topdeck them, with your massive mana production its basically like drawing two for the turn. They don't seem impressive on paper but in practice they're very solid.
I'm not a fan of Demonic Collusion because to me, it's just a bad Increasing Ambition or Diabolic Revelation, and I don't even run those cards in my list. Diabolic Tutor and Planar Portal are too expensive in my opinion, especially the Portal since it costs 12(!) mana to get a single card. Sure, it's reusable and you have no problem generating that kind of mana, but Revelation grabs you so many cards for so much less.
2cmc mana rocks are also deceptively good. Like the small draw spells (which, by the way, low cmc rocks synergize with) they give you something to do in the early game. They're also fairly innocuous, drawing less hate than say, Cabal Coffers, and the incremental ramp adds up over the turns. They are awful topdecks, admittedly, but with your suite of tutors and card draw that drawback is mitigated somewhat.
I found Doubling Cube often sat in play doing nothing, then became winmore once I got the mana to actually make it profitable. I also think Jet Medallion is probably not as good as a generic 2cmc rock, since it can't pay for your artifacts and only becomes better if you play multiple spells per turn, which if you're in that position you're probably already way ahead. Journeyer's Kite could probably be replaced with Liliana of the Dark Realms since they serve a similar function, but Liliana is cheaper and more versatile. Maga can already handily kill people with general damage, but being able to make him go from 11 power to 22 for surprise kills is powerful.
Disruption
I wanted to like Cabal Conditioning but having to have a board presence for it to work turned me off. I also found that mass hand removal isn't necessary unless you're playing a lot of blue players, since frequently non-blue decks have a hard time drawing a plethora of cards. Single target stuff that you're already running like Mind Twist and Mind Sludge are better. If there's a lot of early combo in your meta Duress and Thoughtseize can be great choices to preempt them comboing out.
Ill-Gotten Gains I think doesn't work very well. Sure, you can get people to discard their carefully sculpted hands, but then you give them their best three spells back. I feel that Sadistic Sacrament is probably a better inclusion than Nightmare Incursion. Incursion might be more mana efficient than a kicked Sacrament, but the ability to neuter combo on turn 3 makes it a powerful and versatile choice.
Removal
Personally, I prefer my spot removal to be instant speed, so I dislike Ashes to Ashes and Brainspoil is too expensive even with transmute. Murder and Hero's Downfall might not seem impressive since they're virtual card disadvantage but being able to kill Gaddock Teeg or another problematic creature at instant speed is very good. Dismember is also a solid choice.
Win Conditions
Despite being incredibly thematic, I think the single target drains just don't do enough. Sure, theoretically they can double as expensive removal spells, but often they'll just sit in your hand doing nothing. Besides, if you really want to burn someone out, I'd assume Maga would be the perfect outlet for that. Instead of doubling up on similar kill spells, I'd diversify your ability to win. Cards like Rise of the Dark Realms, Army of the Damned, or good old-fashioned beatings with cards like Lashwrithe or Nightmare Lash. I do like Profane Command though as I really like modal spells.
Utility
Mirari, while cool, is probably not worthwhile. Living the dream and copying something like Corrupt or Mind Twist, but eh, I just don't know. I wanted to include it in my Chainer list for thematic reasons but I couldn't find room for it. I'm not sure about Vedalken Orrery. It seems like it could be great for dropping instant speed board wipes, but otherwise it feels like too much of a do-nothing card.
Anyway. As always, tune the list to your meta, not some random stranger's opinions.
1 Maga, Traitor to Mortals
Land: 38
1 Buried Ruin
1 Cabal Coffers
1 Dark Depths
1 Deserted Temple
1 Dust Bowl
1 Petrified Field
1 Scrying Sheets
1 Strip Mine
1 Tectonic Edge
1 Thespian's Stage
1 Urborg, Tomb of Yawgmoth
1 Vesuva
1 Wasteland
25 Snow-Covered Swamp
Tutors/Draw: 14
1 Ambition's Cost
1 Ancient Craving
1 Beseech the Queen
1 Demonic Collusion
1 Demonic Tutor
1 Diabolic Tutor
1 Necropotence
1 Phyrexian Arena
1 Planar Portal
1 Promise of Power
1 Scroll Rack
1 Sensei's Divining Top
1 Skeletal Scrying
1 Vampiric Tutor
1 Bubbling Muck
1 Caged Sun
1 Crypt Ghast
1 Doubling Cube
1 Expedition Map
1 Extraplanar Lens
1 Gauntlet of Power
1 Gilded Lotus
1 Jet Medallion
1 Journeyer's Kite
1 Magus of the Coffers
1 Nirkana Revenant
1 Sol Ring
1 Solemn Simulacrum
1 Wayfarer's Bauble
Disruption: 9
1 Cabal Conditioning
1 Ill-Gotten Gains
1 Infernal Darkness
1 Mind Shatter
1 Mindslaver
1 Mind Sludge
1 Mind Twist
1 Myojin of Night's Reach
1 Nightmare Incursion
Removal: 12
1 All is Dust
1 Ashes to Ashes
1 Barter In Blood
1 Brainspoil
1 Corrupt
1 Damnation
1 Decree of Pain
1 Kagemaro, First to Suffer
1 Mutilate
1 Nevinyrral's Disk
1 Oblivion Stone
1 Tendrils of Corruption
1 Consume Spirit
1 Drain Life
1 Exsanquinate
1 Profane Command
Utility: 7
1 Crucible of Worlds
1 Grim Discovery
1 Liliana of the Dark Realms
1 Mirari
1 Suffer the Past
1 Vedalken Orrery
1 Yawgmoth's Will
Make big mana, make big spells. Any ideas?
Terrain Generator gets more Swamps into play at low opportunity cost. If you ran more permanents I would also suggest Nykthos, Shrine Nyx. Liliana of the Dark Realms is a great way to search up for Swamps, produce lots of mana and give you more kill with her.
I don't see any Sac Outlets or Bounce to get Maga back into your hand to cast again. Also, since you play a lot of 'all in' spells, perhaps a Boseiju, Who Shelters All?
Mid-Tier: Marchesa Aggro Rose Asmadi Get Dire Tymna Ikra Woke Women Tiana Aura Angel Ruric Thar SMASH Smasher Kraum Mana Positivity Zur Slides
Filthy Casual: WUBRG Jodah WUBRG WUBRG Fatties WUBRG Gahiji Vigilant Vengeance Ezuri Mysterious Morphs
Also Dark Depths probably wouldn't hurt.
https://archidekt.com/user/71716
I think you should consider adding in the cheap draw spells like Night's Whisper, Sign in Blood, and Read the Bones. They give you something to do in the early game, and in the late game if you topdeck them, with your massive mana production its basically like drawing two for the turn. They don't seem impressive on paper but in practice they're very solid.
I'm not a fan of Demonic Collusion because to me, it's just a bad Increasing Ambition or Diabolic Revelation, and I don't even run those cards in my list. Diabolic Tutor and Planar Portal are too expensive in my opinion, especially the Portal since it costs 12(!) mana to get a single card. Sure, it's reusable and you have no problem generating that kind of mana, but Revelation grabs you so many cards for so much less.
Mana
No Crypt Ghast?
2cmc mana rocks are also deceptively good. Like the small draw spells (which, by the way, low cmc rocks synergize with) they give you something to do in the early game. They're also fairly innocuous, drawing less hate than say, Cabal Coffers, and the incremental ramp adds up over the turns. They are awful topdecks, admittedly, but with your suite of tutors and card draw that drawback is mitigated somewhat.
I found Doubling Cube often sat in play doing nothing, then became winmore once I got the mana to actually make it profitable. I also think Jet Medallion is probably not as good as a generic 2cmc rock, since it can't pay for your artifacts and only becomes better if you play multiple spells per turn, which if you're in that position you're probably already way ahead. Journeyer's Kite could probably be replaced with Liliana of the Dark Realms since they serve a similar function, but Liliana is cheaper and more versatile. Maga can already handily kill people with general damage, but being able to make him go from 11 power to 22 for surprise kills is powerful.
Disruption
I wanted to like Cabal Conditioning but having to have a board presence for it to work turned me off. I also found that mass hand removal isn't necessary unless you're playing a lot of blue players, since frequently non-blue decks have a hard time drawing a plethora of cards. Single target stuff that you're already running like Mind Twist and Mind Sludge are better. If there's a lot of early combo in your meta Duress and Thoughtseize can be great choices to preempt them comboing out.
Ill-Gotten Gains I think doesn't work very well. Sure, you can get people to discard their carefully sculpted hands, but then you give them their best three spells back. I feel that Sadistic Sacrament is probably a better inclusion than Nightmare Incursion. Incursion might be more mana efficient than a kicked Sacrament, but the ability to neuter combo on turn 3 makes it a powerful and versatile choice.
Removal
Personally, I prefer my spot removal to be instant speed, so I dislike Ashes to Ashes and Brainspoil is too expensive even with transmute. Murder and Hero's Downfall might not seem impressive since they're virtual card disadvantage but being able to kill Gaddock Teeg or another problematic creature at instant speed is very good. Dismember is also a solid choice.
Win Conditions
Despite being incredibly thematic, I think the single target drains just don't do enough. Sure, theoretically they can double as expensive removal spells, but often they'll just sit in your hand doing nothing. Besides, if you really want to burn someone out, I'd assume Maga would be the perfect outlet for that. Instead of doubling up on similar kill spells, I'd diversify your ability to win. Cards like Rise of the Dark Realms, Army of the Damned, or good old-fashioned beatings with cards like Lashwrithe or Nightmare Lash. I do like Profane Command though as I really like modal spells.
Utility
Mirari, while cool, is probably not worthwhile. Living the dream and copying something like Corrupt or Mind Twist, but eh, I just don't know. I wanted to include it in my Chainer list for thematic reasons but I couldn't find room for it. I'm not sure about Vedalken Orrery. It seems like it could be great for dropping instant speed board wipes, but otherwise it feels like too much of a do-nothing card.
Anyway. As always, tune the list to your meta, not some random stranger's opinions.
[Primer] Erebos, God of the Dead
HONK HONK