This is something that was apparently addressed in an earlier build, which granted it did significantly reduce the frequency of it happening, it still happens and the Habyss event has significantly highlighted just how dangerous this issue is.
Basically, entities thrown by some entities sometimes doesn’t spawn. For instance, Janus throws his keys to indicate where they’ll spawn, or the Stone Guardians throwing their stone sword, but sometimes these graphics don’t render at all, so the keys or sword randomly appear out of seemingly nowhere.
This is extremely fatal in the Heroic Abyss, as the missiles that Malphas throws out can be affected by this bug. I just had this happen to me, the missle spawned on me despite the game not showing the missile being thrown at me, and boom, I thankfully survived with 40 hp. It’s disgusting seriously, I think I’ll take a pass off this event for safety.