Any ways to kill them?
They wll restore health when health drop to 1/3
They can be killed, you just need to deal enough damage between heals
48k dps base was just barely enough to keep up with it on ultimate- i think the heal bubbles need to be toned down.
I am actually not sure on this one. My Battlemage was around 17k Cadence dps, up to 28-ish with Deadly Momentum and Fighting Spirit up, 2200+ to 2500+ OA, some revenge+attack procs… “Huge damage” attacks are Blitz, Oleron’s Might, Cadence 3rd hit and Blade Ark (skills had quite a few points in them, I went only 15 points into Arcanist and got +5 to Soldier skills) with mid-end Forcewave.
I cleared area on Elite with my Dot/Pet Conjurer before, never even noticing the healing shield. When I got in it with BM on Ultimate, surviving was not a problem, killing them became a huge one. I did in 2 sidekicks, but Aldritch kept healing himself. After a few minutes I chain-drank up some potions, like Elixir of the Hunt and blablabla of the Ancients, to no avail. After a few more minutes I began to despair. After a few more minutes I noticed that he seem to have about 1/6 of his energy gone, and morally prepared myself for about 30 min of constant whacking this SoB. To my big surprise after a few more minutes Van Sobich just forgot to heal himself (still having plenty of energy), so I killed him. That last time was I not faster, or anything, he just didn’t heal himself for reasons unknown to me.
Yeah, my BM was build to survive first, and damage later, but wow. Never will I be back in Port before hunting up the rest of Warborn set with him 
(and reading about 48k dps having issues not even then maybe)
Everything is quite simple - try to kill Van’Aldritch first, it is very much simplify the rest of the battle