Not surprisingly, when a team clear a floor and release their record of it, there's going to be people trying to get clears by copying the tactic.
Lem's first job is going to be him making unofficial appearance on the 1st floor helping the dogs there cutting down some of these type.
He mostly keep his power low enough to the level that the party mistaken his work as 'a group of black mages' that's hiding with invisibility magic (break if enemies get too close) and also that he doesn't stand out too much (he is here to help the dogs)
The party assumed that this encounter is either something Phoenix's party just didn't run into during their attempt, or just something they cut out of their recording since fighting black mages aren't very exciting to watch (anyone who's had 60min+ game against Techie in DotA2 can probably agree)
Party got wiped, with the hero of the party taken down by Glas "the invisible slaughterer"
Although after the victory he pet Glas then the other dogs start wanting some too.
And after returning he went to pet the other dogs that were taken out during the fight, and then Cashew who he noticed was giving some envious look at the dogs getting pet.