Burn to Death is your main combo (it only gives out critical hits on DoTs with Prince of Terror, right?), so the difference is large with magic damage accessories. Also, when you use a single-target build with HoE and AoX, you get MSS and Pillars with the same DoT. Once I get T4 rings, I shall parse two similar strawman fights for comparison.
Also, keep in mind that there are two Lacunal Nexus versions, both at level 80, and both blue(!!!) You have to get the +55 MD one, not +52.
Nope. Necromancers have the same bug. Also, I am not sure if Exultation of Xotli should really affect magic DoTs from Burn to Death, MSS, or Pillars.
Coppice is run as a PUG very often. Dugout requires voice communications and is usually run with a group of friends.
The new epic cloak from Caravan, necklace and rings from redesigned HMs are worth looking into; but they might not improve one's damage on account of having less magic damage (cloak), less hit rating (accessories), or being too pink for the demon-god Xotli. I would love to get them though!
PVE: Ideally, 2xRing of Scalding (+hit rating), 1xLacunal Nexus +55, 1xCloak of Waking Nightmares, T3.5 (more hit rating)/BB (easy to get)/T4 gear, T3(high hit rating)/T4/AoK HM (hit rating and critical hits) sword should be my setup.
PVP: PVP T3 cloak, rings, necklace; PVE T3.5 (more armor)/BB (easy to get)/T4 belt, gloves, wrists, shoulders; PVP T3 boots, legs, hat, chest; sword: only Trial of Flame for the armor boost.