[1.6.7] Bug or runaway effect of Overkill?

[tekrunner]

So I was fighting Elandar and Argoniel in NM as an Annihilator. Fight was going ok, I built up some stacks of miasma, then unleashed a fumigate and... died from full (or near full) health. Looking at the log, I somehow took 2k damage from Overkill (I think from Argoniel, but not 100% sure). My guardian turret took 14k damage from it. Elandar took 10k damage from it, and died as well. Looking a bit further up, Overkill had started damaging us all but at lower values, and I hadn't noticed because I had a bunch of blight affinity from using a salve.

I have a feeling that some sort of interaction happened with my guardian turrets. I somehow have 5 "x killed Guardian turret!" messages from different rounds of combat in the log. But I'm not really good enough at deciphering logs to really understand what happened. If anyone wants to have a look, here's the log of the fight until my death : https://pastebin.com/2xaNupTN

I'm pretty sure that this happened once or twice earlier during the run, though not to the same extent. I remember taking large amounts of overkill damage even after I'd kill a boss with the talent, and couldn't really understand why.

EDIT: and if needed character is https://te4.org/characters/9636/tome/7d ... 1a9b6d7fd6