Doom (2016) Invulnerability glitch

Doomguy had enough ripping and tearing and decided to go full godmode for some reason and let the demons kill themselves. I haven t seen this before and I don t know how it happened, but while playing around a bit on the VEGA level I became invulnerable. So I decided to have a little bit of fun with it and clear the last arena without firing directly at a monster. I didn t really plan for this so I killed the last summoner with after some work. This is on nightmare difficulty, no cheats are use