Take the 2-minute tour ×  I recently went through quite a bit of
effort to survive obtaining a key (fire trap in explosive gas
room...). After obtaining said key, I was walking though the
only hallway back to the vault on the level, and it was full of
"deadly lichen" that had not been there earlier.  I would like
to get back to the vault - my potion of detect magic indicated
that all the items inside the vault have benevolent magical
auras. However, but I don't know how to get past this "deadly
lichen", nor am I sure what's its effects on me might be.  To
test the effects, I used my wand of beckoning to pull a kobold
over onto the lichen, and it immediately became "fatally
poisoned" and died within a few turns, so I've determined that
walking over it seems like a BAD option.  So how can I get past
the deadly lichen?  As a bonus, I'm also curious how deadly
lichen forms if anyone knows. It was in the key room, so it may
just be part of an elaborate key trap, but I haven't seen this
before if that's the case, a