what is the dark dungeon good for ?

I think that I don't get better loot from it and there is no auto replay ... with 2 runs in inferno mode in lvl 7-10 I get also much xp and more loot and thatswhy more gold. Just for the power stones ?
Not just powerstones. One of the main reasons people go to Dark dungeon is a chance to get a Dark sword drop upon slaying the Ice dragon. You can get other unique stuff in there particularly Inferno items.

Another thing, it's the only place to get powerstones for free that's why players are grinding their way on that place to collect. A substantial amount of that stone can make your equipment more powerful than standard stone can.
lazyboi
Not just powerstones. One of the main reasons people go to Dark dungeon is a chance to get a Dark sw...
okay thanks
And is it possible to say which is the best way to spend powerstones ?
Ares
And is it possible to say which is the best way to spend powerstones ?
The best way to spend it, is on the sword. Either transcendence (increase tier grade) or upgrade skill damage. Another use is to upgrade the pet dragon to increase damage if you have more. If used on sword, just make sure it's the right one cause powerstone upgrade is not transferrable.
thanks