I do love control, so I'm happy to see this deck so early in pioneer's creation. First of all, I want to address the maybe board: I think that Castles are inherently strong, being non-legendary instant-speed mana sinks essentially stapled onto an island or plains. I would put in at least 2x Sinister Sabotage over Absorb and Syncopate. I would also add a mainboard wincon aside from Teferi, because you have a lot of card draw and if you end up looping Teferi with no other cards in your deck, your opponent can sometimes come back. Also, it's just sort of a pain. Torrential Gearhulk and Dragonlord Ojutai are both very strong options that do things control already likes to do, and Elspeth, Sun's Champion is very hard to deal with. I think Authority of the Consuls and Blind Obedience are both good to have in the sideboard against aggro. Do you have any thoughts on Declaration in Stone vs. Blessed Alliance.

Feltrix: Yeah, I know I should be playing more actual win cons, but space feels pretty tight, so I'm not sure what to cut for them. The reason why I prefer Blessed Alliance over Declaration in Stone is because of aggro. Aggro is going to be strong in this format, so having main deck removal stapled onto lifegain is going to be important.

Considered AEtherling ?? This card was the top-dog during Ravnica-Theros block in every control deck.

In my list i play jace, vyrns prodigy, its a win con. plus he stabizes the board, once things get out of hand flashback a supreme verdict. also i play dragonlord ojutai, great card very hard to deal with. I prefer declaration in stone. it can exile multiple copy of creatures. you may wanna play narset, parther of viels, she is decent not fanastic. your list seems very good fyi