The dwarven gods true names can only be known by dwarves. They are referred to by nicknames in the presence of non-dwarves. I.E. Gudurran( Allfather) Baenna ( Hearthmother) Dudrak ( Ore), etc. No torture or magic or direct intent can reveal their true names to non-dwrves.
Believable magic, like ordinary physicis, operates according to some invariable laws that always result in some kind of cost or "bounce back". The grater the magic, the more it should cost the character physically, emotionally, and spiritually.