@Meddler will we be getting another 100 AP item to replace Rylais?

Rylais definitely needs nerfs, but once these changes go through we'll be losing yet another high AP item. The amount of AP mages end up with over the course of a game has already dropped by about 200 over the past year, and while items that give moderate AP and utility are nice for some champions they're really not what other champions need to function.

Personally I think it would be a good idea to rework Liandry's into that slot since the item's basically always been a painfully niche item that's absurd on some champions and useless on most, and having a more generally useful burn item for DPS mages would be nice because Luden's never really made sense on the champions it was technically designed for, mostly because of the burst potential it offers.