ToME: the Tales of Maj'Eyal

Already forgot about it - does main character invulnurable in it?
Or what?
Strategy and tips forsurviving?
Lat time I deal with it was long ago.

Plz answer because my char in DS now, don't know what to do - to heal, to try to do damage or run dunno.

Lights out!
Survived, and googled for it.

Dididn't think that puzzle in Ruined Dungeon can spawn Dreaming Horror.