Make macros to swap weapons on the fly. Honestly I used Father Time Path B/Raetic Algol+1 to skill chain quick/easily (NQ Raetic Scythe/Algol will work fine). If he starts casting something light based when zombie aura is on; you want to skill-chain darkness and magic burst the opposite element with a tier 3.
Golden Kist hits very weak, but his aura/poison is the biggest threat. Drain 3/Arcane Circle will also give you some room for error and a damage boost/resistance. With a magic evasion set his Stuns/Debuffs don't land as often.
Assuming you aren't using an army of mules:
*On a trash monster:
-Absorb All The Things for a Huge Stat/Acc Boost!
-Pre-buff with Qultada and Immediately Dismiss Him
-My trusts are Cherukki, Sylvie, Ulmia, Joachim, Koru (Honestly they won't be living long at all, and you want trusts that don't melee or feed the monster tp)
-When you are pre-buffed on Absorbs make sure you Magic Burst a Drain 3 for 9999 Maximum HP (weapon bash to a non boosted Infernal Scythe will be weak enough to still MB Drain 3 without killing the monster).
-Go nuts with temp items preopo for Acc/Atk/Etc
-Use a Poison Screen/Arcane Circle before popping.
-Pop in a MEVA set to avoid/mitigate the stun duration.
-Tag it with Arcane Crest, and make sure Last Resort/Hasso is up.
If things end up looking bad, but you came close to taking him down, make sure you land a Bio II before dying. It's possible to salvage a wipe, I don't believe he can manafont again unless he completely regens. It's possible to chip it down while weak with trusts until you are un-weak again.
The biggest pain in the *** is all the pre-buffing, but it ensures victory. I've had a few fights where all of my trusts are dead and it was just me literally soloing the thing. I ended up farming quite a few valorous feet before the DM Campaign.