I just heard from someone on PTS that this is actually a single target proc. What is the point of a dispel / negate set IF IT CANNOT BE USED FOR ZERGBUSTING? Clearly a set of this power needs to scale against groups who could potentially abuse it against outnumbered opponents. This was supposed to be the last piece in the holy trifecta of dark convergence (or rush of agony), plaguebreak and nocturnal's ploy, with which any solo/duo can guarantee a wipe on a ball group with a correctly timed bomb. PB and DC may be overpowered, but they become far more overpowered when you are heavily outnumbered. Here's one simple change that will end tank meta and ball zergs for good.
The 5 set bonus needs to be:
(5 items) When you apply a Major Debuff to enemies, remove one Major Buff with a duration from the target for every target debuffed. When you apply a Minor Debuff to enemies, remove one Minor Buff with a duration from the target for every target debuffed. These effects can both occur once every 2 seconds.