Dungeons are special instances where you can kill unique monsters for huge loot. Dungeons are not automatically available on a new character. They must first be unlocked. This most often happens via quests.
After a dungeon is unlocked, you also have to have enough available runs to fight in the dungeon. These are typically earned via daily quests. Each dungeon has its own dungeon run. Dungeon runs do not have to be used straight away, and if you choose to, you can save them up for use at a later time as they stack.
Dungeon rewards are typically large amounts of crafting materials, upgrade items, or unique crafting reagents.
Some other important things to know about dungeons:
- You can kill a maximum of 1 monster per action while in dungeons.
- Dungeons require a certain number of monsters to be killed to be completed.
- Completing a dungeon lets you roll once on the dungeon's drop table, and also lowers your number of “available runs”.
All dungeons are unlocked by following the main quest line.