Okay after dealing a few damage to him use break on him and pray that roald either shell shocks or silences that cockroach after break wears off if not use disrupt to drain it's focus make sure to equip 2 of them or use subversion when you are thinking hes going to heal
you people have really bad strategies, i cilled him in 1 hit!!!! i was level like 13 or what ever level you should be. this is what i did to over kill the bit**. first use predetor from, then shadow blend, then sharp senses and finish up with slash. i over killed his little ass.