This build is pretty crappy when it comes to any fight with fewer than 3-4 mobs. It also sucks if the mobs die quickly, or if you're targeting a mob that dies faster than the rest. You're looking at 5-7 GCDs to get rolling, but then it starts paying off in spades.

It's a 61 Defiler build with AoE radius increase from Cab and range boost from Inq (as well as pushback elimination).

61/13/2

It's a reasonable-ish rotation - basically a Defiler segment that cycles on Unholy Nexus, and a fairly standard Cabalist spam:
  • Start by applying Marrow Harvest, Siphon Vitality, Bond of Pain, and Bond of Torment (optionally), then spread with Unholy Nexus. Keep an eye on these - when Unholy Nexus comes off CD, your target should have all active, especially Marrow Harvest!
  • While UN is on CD, Pain Transmission (better with more melee!), Tyranny of Death, and spam Bound Fate.
  • Weave Feedback into this (no more than once every 3 damaging casts!) if your link targets are taking damage.

Tips:
  • Unholy Nexus is off GCD. This is awesome.
  • Siphon Vitality refreshes Husk of Indifference. Don't cast Husk of Indifference directly.
  • If adds are joining the fight, you may want to delay use of Unholy Nexus until they're all in range
.

Outstanding Issues:
  • Does Broad Strokes affect Unholy Nexus?
  • Does it makes sense to use 5 points in Entropy (+10% for DoTs and Delayed Damage) or in Secrets of the Deep (+5% overall)? I need to parse out a few encounters.
  • Is it a DPS gain to open with Curse of Solitude?

Final thoughts

As a 61 Defiler, you have access to Unstable Transformation. Use it as an extra CD for the tank, or to get someone out of trouble. Communicate its use - despite the model replacement, many people won't actually notice!

Defiler also brings a combat rez with only 32 points allocated. Again, awesome. You'll likely be in a better position than the tank to recover any healers who go down.

I'm pretty sure that Unholy Nexus sets the max timer on the things that it spreads - but it doesn't reset the timer on your target.