Invis works against him.
At level 50 I went to try my luck at camping the ac, but wasn't sure where the spawn was exactly. I wandered around the island a bit and this was the only spawn I found so I tried to kill it since it conned blue. Almost killed it but he caught up with me in the end and killed me without much hp left at all (I don't think he runs when low on hp, but I could be wrong). I probably would have died anyway if I did kill him due to the level 52 corrupted that spawns immediately, but I wouldn't have lost so much exp from the death =(