I'd put about 3 Spell Swindle in the main board. Even if you only counter a 3 cost spell that's still more mana to play Nicol Bolas, God-Pharaoh faster or 3 more X in Torment of Hailfire. Then you cast it again with Torrential Gearhulk. I'd probably swap 1 Opt and 2 Supreme Will for them.

Thank you for the suggestion, Toxic5pikes! My only complaint with Spell Swindle is that it is 5 mana, so even with the possible payback, it is often too slow compared to Disallow or Supreme Will. The only use I would have for it is against dinos, because RDWs are much too fast for this, and the payback is too little. Supreme Will can also be used to dig for a Torment of Hailfire or similar, and can also be flashed back. I think I will take out one Torment in the side and put in another Swindle against dinos.

This deck is well-built already, so I'm skipping straight to some suggestions--

In playtest, the weakest cards were those that required BB, especially Bontu's Last Reckoning. Lost Legacy is too slow for the mainboard in my opinion, it only really instant-wins vs the Approach of the Second Sun decks and is card disadvantage in many other matchups. You weren't doing enough damage for Torment to work as a finisher: It's weaker than Bolas at x>5 (CMC>7) and uncastable at x<5. I therefore recommend you change your double-color colors from UB with red splash to UR with black splash. Cut lost legacy for 1-2 lands to shore up your double-colors (preferably duals like the cycling ETB tapped ones) and to ensure mana consistancy for your Pull from Tomorrows, and replace Bontu's Last Reckoning with a combination of Sweltering Sands and Hour of Devastation (all strict upgrades IMO). The big loss here is Vraska's Contempt, to which there is no real comparable substitution for without double-black - you still need some way to deal with walkers.

For the sideboard, I'd cut the ferociodons, spell pierces, and BB cards, and put in an extra copy of each of your wraths and a number of (negate + duress) cards equal to the number of removal spells you have that are dead in control matchups.

Overall, a very solid deck!

Thank you for the feedback, randomguyguy! Lost Legacy will be put in the sideboard, because it really is a good card against most decks in the format. I can kill Approach decks with it, and I can also cast it a turn before a Hazoret, and that's a huge deal against RDW. It's also great to completely remove Carnage Tyrant before it ever ETB. I will look into getting some Hour of Devastations, I kinda forgot about that card tbh. I will likely cut Bontu's Reckoning for them and/or Sweltering Suns. Should I therefore include Chandra?

I would say cut down the Torrential Gearhulks to 2 of, 4 is a bit much as drawing 2+ early is dead draws. Control decks also generally want 25-26 lands. I've enjoyed using torment, but it often take 10+ mana to do good with it, so i prefer Cut/ribbons (ribbons makes for a surprise ender as it gets lost in the grave). Finally, Glimmer of Genius is 1 of the best draw spells atm.

Last thing is to cut down on the double-color-costs. I don't think you can reasonably hit Vraska's Contempt on 4, Sweltering Suns on 3, and Disallow on 3, or even get all six colors (RRUUBB) by five mana consistantly, especially with as few duals and lands as you're playing.

https://www.channelfireball.com/articles/frank-analysis-how-many-colored-mana-sources-do-you-need-to-consistently-cast-your-spells/

This article recommends 17-18 sources of each color to cast double color cards on curve on turn 4, and 18-19 to cast double color cards on curve on turn 3.

Thank you taiga277677! The gearhulks are an absolute must-have. They are huge bodies, and flashing back a Glimmer or Contempt is often game-changing. I have included both Cut/Ribbons and the Glimmers, so thank you! Also, thank you randomguyguy (again :D)! I have completely revamped my mana base, and it is a lot more consistent now.

imo some cheap spells that make treasure for you would be pretty helpful

Thank you for the input, dotytron. What spells would you suggest, and what would you replace?

Deathgorge Scavenger i would sb and Naga Vitalist i would drop and add in two Sailor of Means if you need those slots to be creatures and Depths of Desire or Pirate's Prize for more spells

Awesome list! I'm thinking of building something similar as it throws together basically all the best bomb cards in standard that I own. One thing I'm not sold on however is Attune with Aether. Do you feel you have enough green mana sources to reliably play it? I feel like Spirebluff Canal would be better suited than Rootbound Crag and Sheltered Thicket. I also might consider cutting a couple of your higher end cards for Fatal Push. Thoughts?

Thank you, KingkillerKvothe! I'm glad you like the list. Now, Attune with Aether is a great card for me, because it allows the colorfixing I need, running a mana-intensive deck like this. Plus, the 2 energy can fuel my Aether Hubs or a Harnessed Lightning. I understand the hesitation, but it has really been useful for me, and I can reliably cast it. Now, I did originally have Spirebluff Canal, but I decided that the checklands are better in the long term game, which is where I like to take this deck. Plus, the dual lands can be cycled out as needed as well. As for Fatal Push, it comes down to personal preference and availability. Hope this helped, and good luck with your deck!

This seems positively bizarre, do you ever run into mana problems? I'm running a deck with similar win cons, but mine is a primary black deck with blue and then two red cards in the main and one in the side.

How does the attune package and vraska tend to work or for you? Also you have red removal when black removal can often do a better job, any reason?

Thank you for taking the time to comment, Dickified! In testing, this deck is actually pretty consistent! The Attune with Aether is a great card at any point in the game, as I can fetch whatever land I needed and get two more energy for 1 mana, in turn keeping my Aether Hubs up and running or fueling a huge Harnessed Lightning. Vraska is an amazing card as well, as her abilities are so versatile in this deck. Her tokens are great blockers, and can sneak in for a few extra damage later on. Being able to remove enchantments is huge as well, especially because we aren't running white. Finally, her ultimate will win the game, and can undo a game's worth of lifegain for my opponent. Because this is a very lategame deck, this is vital against decks like Vampires and even Approach. Tl;dr she is an absolute must in this deck. As to the removal, black is often much more efficient, but the only really good black removal spells are Fatal Push and Vraska's Contempt. I have the Contempts in here, and while Push is a great card, I can't use it against most dinos or any of the gearhulks, while Abrade is very versitale and Harnessed Lightning can hit anything with enough energy. I hope this helped!