The Wide Brimmed Hat fire bomb, dagger wielding risen that is part of the Risen Raids daily quest simply disappeared after dying to the thorns reflect damage from the Corpse Smeared blade. Quest did not complete after he died (he was the last Risen of the three i had killed.
Came back a little while later and he and the other risen respawned. I tried to reproduce the bug using thorns again and found success. He disappeared on death again, again no quest completion.
Upon returning a third time shortly after , i killed the 3 risen normally, in the same order without using the thorns effect, and they died normally, and the quest completed successfully. I have tried to see if the thorns makes other units vanish, and have not found any other instances.
Noticed something similar in the Crucible. When enemies die from reflect/thorns they would occasionally not drop any traces at all and just stand there in default pose.
Its not strictly restricted to the Thorns rune. Damage reflect/Thistle ring/Damage dealt on damage taken result in weird behaviours. I have several things that should not happen and will post them later on here.
So far I found 2 things that interract in a weird way with damage reflect/thorns .
1)The enemy that spawns worms on death will spawn them Endlessly if the explosion hits the player character that has damage reflect on.
2)Sometimes the enemies will not drop any traces when they die from Damage reflect of any kind.