After killing a mob, hostile vexes will continue to be hostile and will do their lunge attack towards the location the mob they were hostile towards died.

How to Recreate:

1.) Summon several vexes

2.) Summon Iron Golem near them

3.) Wait for the Iron Golem to attack a Vex

4.) After the Iron Golem attacks the Vex, it will cause all nearby Vexes to become hostile towards the Iron Golem

5.) After the Vexes kill the Iron Golem, they will continue to think the Iron Golem is alive and lunge towards the location where it died as if it was still alive.