Hey guys, returning player here.
So for 0.9 i put up a Lich build, which i partly copied from other (older) popular guides, with some of my own adaptations and also some necessary changes, (because some of the trees have changed a bit since 0.8.5).
For my core rotation of skills I have Reaper - Death Seal - Transplant and Rip Blood. I like the playstyle very much, in that I pop Reaper, then Death Seal and see the hordes melt while i just phase through. But I’m not sure about the last active skill. In the previous builds (and my offline char), I have Bone Curse there, with Mark for Death which lasts indefinitely, but I’m not sure if it’s of good use, as I thought I would rather like some more offensive/defensive/utility skill or buff there, which I occasionally use either on cooldowns, or just while running.
So, is Bone Curse still kinda the “go to” on a somewhat regular Death Seal Lich build? I started fiddling around with Soul Feast, but not sure if it will be of much use, as I’m not sure if the interactions of additional armor due to poisoning, and then maybe converting that to armour shred are actually working. And then there’s also the node which doesn’t rely on cursed enemies at all and another one applying Damned to enemies. 
I didn’t check all other skills with all nodes yet, so maybe there is another alternative which would give either offensive or defensive buffs or some other benefits like atk/cast/move speed or general QoL ? 
Last question would be: if I keep Bone Curse, will the Transplant node Doom Bringer use my specced Bone Curse with all its nodes and does it generally make sense to use it together with Cursed Exile ?
Thanks in advance