Thanks everyone for the tip
Regarding lucky shot i really think that is an issue in IVAN : I died countless times by a one-shot from a weak ennemy. Critical hit in games are ok, but theses seem really too powerful and you can't do anything against them. That's a bit against the "rules" of roguelike to have something you can't avoid : Roguelikes should be hard but fair.
I remember that one of my best guy with lot of good stuff was in GC 1 and killed a wolf in 2/3 attacks and lost between 0 and 5 HP (can't remember exactly) . Then he moved a bit, found another wolf, the wolf made a lucky shot : goodbye head, goodbye life, goodbye good stuff. -_-