Abyssal Scepter Trying To Be Magic Equivalent To Black Cleaver?

If that is the case that is kind of dumb. You would need to be around someone for 12 full seconds to get the 30% MR shred.

I am not sure on the range of this emulating pulse but if it's meant to be Melee range then this is going to be a garbage item.

For example Black Cleaver has the same exact resistance shred but it is applied by physical damage. You are going to get the armor shred from black cleaver a lot faster than Abyssal every time.

tl;dr Abyssal MR shred is garbage compared to Black Cleaver