[Radek]

The "It missess" message seems to occur when the monster is ready to hit but, for some reason, it cannot hit. This can happen:
- if the monster is killed before it gets its turn, or
- if you teleport away before it gets its turn.
The condition for the message seems to be that either you or the monster isn't here when the monster should hit - the monster is dead or you have vanished.
The "dead mummy gets deader" seems to occur when
- the monster casts an area-effect spell (for example Flamestrike) in the moment when you kill the monster, and
- if the monster is in the range of the spell.
You kill the monster and get the message "mummy is dead" - and then the spell hits the dead mummy and you get the message "dead mummy gets deader".
Both these effects seems to be the result of a not good management of event queues and object statuses. The mummy is dead but its event queue still contains events like "hit the enemy". The Flamestrike spell tries to hit the dead mummy. And so on.