It's the Vein Orchard (-1 max HP on hit), consistently bugs out and doesn't finish combat if you melee-kill it
And yes, I have both died to the 5% instakill and lost my weapon to the corrosive bastard TWICE, ON THE FIRST HIT.
Good thing I got the Khorne Roleplay Juice Thingy and just SKULLS FOR THE SKULL THRONEd the rest of the f**kers