This happened in Coven All Any.
It was me (trapper), a trans, an amne and a CL (had necro) left. I trapped the trans and said trans to trans me with the CL. The CL attacked the transporter so triggered my trap. Somehow he was alive at the start of next day and the amne remembered Potion Master. It is certain that the CL was not healed, and he triggered my trap. Even though the trapper has powerful attack and should be able to kill CL with basic defense.
I don't know how to recreate this but it may be cause form the CL being transed?
Hope it gets patched soon so that people do not experience this again.
Thanks in advance.