Running only Curses and Soul Reap (with whatever's left over in Death for Soul Feast, if desired):
[skill]Suffering[/skill][skill]Faintheartedness[/skill][skill]Enfeeble[/skill][skill]Wither[/skill] or [skill]Reaper's Mark[/skill] or [skill]Icy Veins[/skill][skill]Signet of Lost Souls[/skill][skill]Soul Feast[/skill][skill]Resurrect[/skill] or related skill
[skill]Wail of Doom[/skill] is a bit of nasty fun.
Possible substitutions (non-Nightfall skills): [skill]Weaken Armor[/skill][skill]Malaise[/skill][skill]Reckless Haste[/skill]with[skill]Price of Failure[/skill][skill]Rigor Mortis[/skill](good for Factions, I find)[skill]Enfeebling Blood[/skill] instead of Enfeeble for more degen goodness
[skill]Well of Silence[/skill] works very well in Nightfall.
You can trade out Soul Feast for Antidote Signet (ranger secondary) if you're in an area with a lot of Blinding and Poisoning.
Energy is less of a problem with Signet of Lost Souls, but if you don't have NF, you really shouldn't have much trouble, especially if you're using a max offhand and a +5^50 egy weapon. Of course, a good team helps immensely

.
Trust me, this is a very useful little set-up (although, of course, it probably can be improved upon).