That AP is kinda really pathetic.
If it's gonna be an offensive/defensive bruiser item then give it some actual AP and not top tier MR.
This is really a strong buff to existing AoE magic damage dealing TANKS like Ammumu and Sejuani.
Abyssal Scepter is something I really want to be able to get when I'm more offensive focused on any close range AP champion. When I'm willing to sacrifice a bit of offensive power for resistances (like building it instead of Void Staff when they're not building much MR, or i'm not the main damage source).
Even if they make a new item with decent AP+MR, that one probably won't have any mPen of any kind.
The new passive looks interesting enough, but the low low AP just makes it so unattractive. When I'm a bruiser or an AP champion of any kind, I wanna deal damage and pressure using my abilities, not fiddly passives on items.