Monsters get first move
Again, not sure if this is a bug or intentional behaviour, but in recent versions monsters seem to get the first move when you enter a new level. It's a bit harsh if you happen to get next to a greater moloch, gorgon, emperor lich or any other potential instakiller - you're left with not a single chance to escape or prepare for it. Not sure when this changed, it was some versions ago.
The original way was IMHO much more merciful by giving you the first move.