For the completion reward, I already wasn't really expecting much considering how easy the dungeon was but even then I was disappointed.
Katsuki received a wooden bucket of all things…
I realised I didn't get anything and Sebastian explained that because I didn't participate in the fight, the dungeon had not given me a completion reward.
Feeling unsatisfied with that, I asked to fight the boss as well so we left the boss room to allow it to respawn before entering it again, this time with just me fighting it by myself.
The fight against the boss couldn't even be called a fight as I simply charged up my [Laser] as much as I could before firing it off, killing the boss instantly.
And… The reward I got was a comb.
At least it was still better than a bucket but I didn't really need it so I gave it to Katsuki, who seemed over the moon to receive it for some reason.