I'm honestly surprised he hasn't tried using his tail as a weapon yet.
It's a heavily muscled appendage with spikes, that quite easily shattered concrete and stone into tiny fragments.
I'm glad that their is actual work the MC has to put into understanding, using, and getting his powers instead of most where the MC is instant OP. I am also glad about the character building, world building, and pacing.
It really is extremely irresponsible that he hasn't relayed the information about fallen players creating these dungeons; I'm sure they can figure it out eventually but a lot of lives could be saved by carefully keeping track of where players fall and then keeping players of suitable skill level relative to who died posted around the area.