Yeah, I don't want it to be overpowered or lacking an identity, but I would like it to be core on a larger group of users and a good situational choice for a bigger chunk of the roster.
Back before the rework and recently on Twitter, I suggested this:
60 AP
400 HP
Unique Passive, Eyes of Pain: Dealing damage or applying crowd control to an enemy champion increases your bonus magic penetration by 6%. (1 second cooldown per target, max 5 stacks)
Unique Passive, Torment: Magic damage burns enemies for 1.5% maximum health per second for 3 seconds. Impairing an enemy's movement burns them 2.5% maximum health per second for 2 seconds.
The point here is to make this a viable AP bruiser item with DoT synergy. Important to note that the two dots are independent of each other and can tick at the same time.
Lower AP is deliberate to dis-incentivize burst mages and assassins picking it up as a top damage item or to just increase TTL. The bonus % pen targets its power towards tanks without having too broad appeal. And like Black Cleaver, it has some anti-synergy with Void Staff and flat pen while still being strong against MR stackers.
On paper it might seem too strong, but when I compare it to Black Cleaver and Adaptive Helm it seems fine. Then again, AP items are literally always worse and more pigeonholed than other classes, so I'm not expecting much.