Bricked map bc of rare mob bugged on death

Vaal Factory map, rare mob died, but it continued to attack and roll after me (at a glance 2 spider front legs and rolling ball for hindbody. it's spamming multi-directional projectiles so I can't get close to study it). the mob no longer targetable, I couldn't damage it and it wasn't going away in any sense. With that bugged mob on the map, the map remained unfinished and I had to abandon the map