Blackjaw slowing bug

Im fight with Blackjaw , i clear a all the map easy , when i start the fight with him, im started to be REALY REALY REALY REALYYYYYY slow .. for no reason , i watch my buff, my curse and all and any mentionne slow speed or slow cast speed or what ever. He dosent have Aura or what ever , JUST A BUG ... he's create a invisible slowing aura .. and im die ... yeah ... funny ... im come back and the bug dosen't appear and in 2 min i kill him .. bug with the bug, he kill me because im slowed like 80%-90% ... it's very terrible , do something pls for people play hardcore mode...