Any list with this needs Dark Ritual, and probably other fast mana (Elvish Spirit Guide?). So I'd add that.
I'd add 2 more Ouphes, 1 Null Rod, and 1 Chalice of the Void. Need to deny their moxen.
Cut Liliana too slow. Cut Demonic, and the Symetries. Also too slow.
I'd try with the 3 Maralen, but probably cut that 1 eventually. That's just a random finisher for the game. You need a lock before you can play her.
I don't think I would ever cut Demonic Tutor. I can't see how it's ever too slow, especially with rituals. And Scheming Symmetry seems great also.
I'm looking at blowout lines of play such as... flash Agent EOT (or earlier in the turn depending), and on your turn cast Symmetry, find your best card, find their best card (ancestral?) Their ancestral doesn't go on top of their library, it's exiled and you can play it and pay any color mana (notably for this deck, B.)