Yes... but now we need a (tough) boss that has healing + vulnerable to curse, or fort + vulnerable to curse - and there are precious few that qualify.
Of the top of my head, reasonably hard enemies where one might bother with this:
- Harry the Angry Little Pit Fiend - nope, immune to curse
- Sally the Horny Little Devil - nope, immune to curse
- Horoth the Angry Bigger Pit Fiend - nope, immune to curse
- Bosses in new Shavarath quests - way too easy to bother with.
- Jolly Green Giant Lich - Meh. Mild benefit since he burns rather nicely.
- Abbot - Perhaps, would need testing to see if it can even land.
- Running with devils named Eladrin - should help, specially when doing the quest at low levels (say 12 or so?)
...I think I'll take my 25% extra healing and caster dps, unless someone can add some (significant) enemies to the list, which I may be forgetting?
But I have always been meaning to ask ... why the 'eck ARE Harry and Sally immune to curse? You know, if you remove that little (annoying as heck freebie) pseudo-buff that negative energy thing becomes a lot more useful..