Keening Stone might be a good addition as another win con, it is pretty mana expensive if you want to use it as a surprise though.

The main problem I see with Keening Stone is the mana cost. Even if I don't activate on the first turn 5 per activation is a little steep and on most turns that would take up most of my mana. Comparatively, Sewer Nemesis and Consuming Aberration provide additional mill via abilities, can usually block creatures of any power as soon as they hit and are free to activate after the initial investment. Also I can untap them with Umbral Mantle or Thousand-Year Elixir

This is already a highly tuned deck. Not sure i can suggest some improvements.

Maybe you can try Havengul Lich for reanimation and Paradox Engine for untap shenanigans.

Also i think Deranged Assistant is an odd one.

My Decepticon has been shelved. The pieces currently sit in my Mind. Please have a look and suggest if you could.

Deranged Assistant, in addition to being a rare blue mana dork. Is mainly in there for a combo I found for Necrotic Ooze when it shares a graveyard with Pili-Pala. I can mill my own library at mana speed and briefly access every activated ability, including Tree of Perdition and Eater of the Dead.

Paradox Engine doesn't really shine in a deck with such a heavy focus on permanents over instants and sorceries but Havengul Lich would certainly be useful. Especially in conjunction with Teferi, Mage of Zhalfir. Unfortunately, I'm not sure if there's a card besides Teferi that I could swap for it.

you definitely need a Mindcrank to party with your Duskmantle Guildmage

Ah sorry, just read your description... you left it out intentionally. anyway, great deck, +1

dooomsdae thank you. I appreciate it!

If you like Mindcrank Check out my duskcrank deck.

The only card I can see is dark impostor, although that i just from personal experience. I've included him in several decks, but I've never really gotten much use out of him. If he works for you then that's my only switch suggestion.

I would say take out Dark Impostor in exchange for Liliana, Death's Majesty. His activated ability is way too expensive, and though he seems like he might be a cool card, he is too expensive to actually use. I've played a few games against him, and he looks scary, but that's the problem. Once you play him he'll become a target and will be destroyed before you actually get to use the ability.

That's just my opinion, have you been able to use his ability to a good extent?

Usually Dark Impostor Caries his own weight, I'll always make it to 6 mana and a 3 mana creature that demands removal Is pretty useful. I was looking more at Oona or Koshuko

Two other cards I think you might also find use for would be Bonehoard and Nighthowler. Especially in larger games, these cards can one shot a player if they aren't countered. Play a creature first, then play and re-equip or bestow for an extremely painful mill, and both have durability to creature destruction. Both can be equipped to an existing creature for a surprising blow or played alone to draw out counters or kill spells.

My personal recommendation to remove would be, as i said previously, Dark Impostor as I've only very rarely actually used his ability because he's often killed before I get any use out of him. He lacks durability and unless you have 9 mana or it's a small game he will likely be dead before you have the six to throw at him, or at least that's my experience. I do agree with Barsan that Oona, Queen of the Fae or Kokusho, the Evening Star are both cards that aren't as functional in the deck as others however, and you may wish to find alternatives. if they work for you, more power to you, but Kokusho especially doesn't really play to this decks theme. If imposter is in place for removal there are better options.

Have you thought about running Mind Over Matter ?

nerdpwner739 I certainly have. In a much older version of the deck I ran both Mind Over Matter and Temple Bell . Mind over Matter went first due to it's high color weight before I even uploaded the deck and Temple Bell held out until 27 September of 2018 where I replaced it with Mikokoro, Center of the Sea