Mill yourself like in Abzan Rites, but with Esper tech. So we use Stitcher's Supplier, Thought Scour, Thirst for Knowledge, and Champion of Wits to get stuff in the yard. We have Condescend and Countersquall to protect our graveyard, and can blink our Gearhulks for their ETBs with Restoration Angel. Torrential Gearhulk lets us double dip on instants, which in this case means card draw, cantrips or counterspells. Silumgar's Command is in here for this very reason - we can get a lot of value by getting it back with Torrential, and in the late game we'll have the mana to cast it if necessary. It being a counterspell and creature/planeswalker removal is actually pretty versatile, and the bounce clause is occasionally relevant against Tron (you can, for example, bounce a Tron land and destroy a Karn). It's not to be relied on to hate on decks, but it's versatility makes it a flexible, strong choice. Same goes for Collective Brutality, which is what we want when we want it. It also dumps stuff in the yard. It's good. It's also the single most expensive card by far here, so if you want to go budget you could take it out for a second pair of Thirst for Knowledge and a pair of your removal spell of choice.
We play a one-of of Sphinx of the Steel Wind because, in the right matchups, it's essentially unbeatable. It completely hoses green and red decks, gains us life, flies and is a dangerous attacker and blocker. It's rad. However, it doesn't have an ETB, so we only play the one, since it doesn't have any particular synergy with Restoration Angel.
Lingering Souls should be a 4-of, but I'm unsure of what to cut to make room. I need to playtest this a lot more before I'm sure of what it replaces; it's capacity to just win games on its own is not to be underrated and it's a fine backup plan for us.
Champion of Wits is looting on a stick that gets quite a bit better in the late game when, if the game goes long, we can eternalize it to refill our hand and get a nice beater. It's kind of like a crappy Bedlam Reveler with early game-upside, which is still a fine card.
We run a low land count, but we have enough looting that getting to four lands should be fairly easy. Obviously, a competitive build would run fetches/shocks, but I still haven't invested in those, so this is what I'm running as a makeshift until that happy day arrives. Taplands suck, but getting us all our mana colors in one go makes Arcane Sanctum arguably not the literal worst. You do you here - this mana base is made of cards I have already, and odds are you have better ones, so go nuts. I'm also considering running a 2/2 split of Irrigated Farmland and Fetid Pools for the cycling upside in the late game.
In the sideboard, we have Cataclysmic Gearhulk to round out the trio. This guy is not great, so if you're going for optimization, cut him for a pair of Wrath of Gods or what have you. He does, however, wreck decks that go wide for the win or rely too heavily on one permanent type. This does mean he will randomly hose Bogles or Affinity type decks (if you live that long, lol) while also providing a strong body. He's mostly here as an honorable mention, but he's not completely useless. He does have an interesting synergy with Restoration Angel, in that blinking him with one will let you choose him as the artifact you keep and the angel as the creature you keep.
Everything else is pretty standard. More Condescend for when needed, Damping Sphere to hose Tron/Storm, Nihil Spellbomb for graveyards/card draw, Murderous Cut for removal, and Fragmentize for artifact/enchantment heavy opposing decks.
This probably changes with some of the new surveil cards from Guilds of Ravnica, though I haven't evaluated them closely enough to really come to any conclusion.
EDIT1: Swapped Thirst for Knowledge with Gifts Ungiven. Gifts just seems so strong here; you can go for a two card package of Unburial Rites and a reanimation target (Sphinx of the Steel Wind is probably best unless you really need a Gearhulk ETB) or you can get fancy and go for Unburial Rites + Resto + a gearhulk + Lingering Souls if you're feeling especially spicy. This works best if you're at six mana, in which event there just isn't really a right answer. If they give you the Gearhulk and Lingering Souls, you get two castins of Souls and two ETBS for the Gearhulk (provided you reanimate the Resto and blink the Gearhulk). If they give you the gearhulk and Resto, you get to cast it, blink it, and reanimate something else while still getting to cast Lingering Souls with flashback. There's no real winning combination for your opponent, though again I would emphasis this works well only if you have six mana. Otherwise, stick to the two card package so you can get Sphinx out or get a needed ETB from a Gearhulk.
I also realized Fragmentize is a very dumb choice, because it's not an instant. Disenchant is clearly better because it's still reasonably cheap and we can flash it back with Torrential Gearhulk, and it can hit things like
Hollow One
. That's an edge case for sure, but it does matter.
Additionally, I really feel like Path to Exile and Mystical Teachings should be in the deck. I'm just unsure of what, exactly, to cut to make room. I could see an argument for moving x2 Collective Brutality to the sideboard, but the versatility of that card is such that I'm a little unwilling to go down on it. Possibly we could go down a Silumgar's Command (possibly moving it to the sideboard) - to be frank, I just need to play the deck more to get a feel for what's extraneous. Path is useful for dealing with early creatures since we have Noxious Gearhulk potentially from turn 4, but Collective Brutality is also good at that. Possibly we just go for a single Path to Exile. Settle the Wreckage also seems relevant as a boardwipe that we can get back with Torrential, making it a potentially valuable Gifts target. Mystical Teachings just binds the deck together by having flashback (meaning we're cool with milling it), being an instant (hello Torrential) and getting a number of our more crucial spells like Torrential and Gifts.
EDIT2: I suppose there's no real reason not to run Elesh Norn, Grand Cenobite for our prime Gifts target. Once I get it, it'll probably take Sphinx's spot. I do love Sphinx, so that'll be sad but probably for the best. In the meantime, we're adding in Blood Baron of Vizkopa so that, betwen it and Sphinx, we can get protection from 4 of the 5 colors on an aggressive body, and the 5th color (blue) is not known for it's hard removal. This gives us a flexible beater that should bait out board wipes or simply end the game. I could see an argument for mainboarding it, but I prefer to run it in the sideboard since Sphinx is more generally useful.
EDIT3: Traumatic Visions is a card that, weirdly, may be a good fit for our deck. We can landcycle it to help us hit our colors, and being able to do so is actually pretty important for a deck with a very budget manabase. Additionally, we can get it back with Torrential for a straight, no-frills counter spell. It might be a little too cute for the deck, but I think that there's a real chance it's a good inclusion. It gets us land early and is, unlike Silumgar's Command, a straight counterspell.
