Demonic
Demonic was the item I was most hyped for when you guys were showcasing the preseason items. AP Bruiser Sylas was by far my favorite thing to ever play in League, and I was still making it work after the removal of the shield with the ROA + Nashor's Tooth build (admittedly not the best, but it worked for me in low diamond and normals).
Demonic was great for all of like two weeks, and then people figured out that you could double-down with an overtuned Liandry's burn and build both items on literally every mage to turn everyone into an artillery Brand.
IMO, Demonic feels like a joke at this point, the resistance gain is pitiful, and the item just feels weak in comparison to any other non-troll option for a 2nd or 3rd slot. I'd much rather give up some of the upfront damage/AP for more resistances, or a ramp-up to the burn, or some CDR/Ability Haste. In Demonic's current state, it feels like it's doomed to be a weak item or it'll be abused by other AP champions opposed to the intended users.
Ever since Season 11 started, I've kind of just dropped playing Sylas, and he was my second most played since his release. Bruiser Sylas just feels inferior to full AP 1shot builds. Everfrost and Cosmic changes kind of brought it back a little, but Demonic still feels like crap.