Cloaker
What is your strategy for confronting the fantasy creature Cloaker in Dungeons & Dragons?
More info on this creature: Source 1
The long and short of it is "always look up and down". The monster description specifically had this (pretty sure it's this, or some similar big floaty dark thing that envelops you) as usually hanging out on the ceiling to drop down onto people's heads, or camouflaged as rugs. I spring them a number of times on players, and always felt a little guilty doing it because they're almost too easy. Fire, I think is a good solid defense, though I continue to protest an actual burning torch only doing 1D4 damage.