When attacking and using lightbeam, sometimes the player loses the ability to attack at all (both normally or with abilities). This also appears to make your player immortal when they die and respawn(?) (see screenshot).
To recreate:
Raise a Life character (I used Witch of Life) to level 4; then, attack and use Lightbeam against an enemy. Spamming both helps to create it more consistently.

Screenshots:
https://gitlab.com/thegenesisproject/thegenesisproject/uploads/517ca7209547d4c19838929a5b0b19d9/279_unknown.png

Player log:
https://gitlab.com/thegenesisproject/thegenesisproject/uploads/9e365b6ae22679009d387e89b2778fc4/394_player.log

Originally reported by lomour#5498 (lomour)

Internal issue ID: 315