User blog comment:Zilla4444/AP Version of Black Cleaver/@comment-74.69.6.81-20120614113422/@comment-5009341-20120614120856

aoe skills proc it, just: abysall give 40 ap less and 57 mr more (only good if u have strong enemy mage against u), further more it will give ur presence away (due to the debuff)
 * The buff wont be applied, by toggle abilities (such as Singed's poison trail)
 * The buff will only be applied once per cast, DoT-effects will apply the buff only once (Morgana's Tormented Soil, Karthus' Defile).

now that i compare it to abyssal i see how much inferior it is actually (i nerfed it multiple times, cause some people kept complaining

what shall i change?

1. the item cost

2. the ap

3. the cdr

4. the mrpen