Diablo II/Den of Evil

, High Priestess of the Sisterhood of the Sightless Eye, gives you this quest after introducing herself when you interact with her in the south corner of the Rogue Encampment. Although optional, it's definitely worth completing for the reward.

If you talk to anyone before leaving the camp:

Blood Moor
Follow the path away from the bonfire in the middle of the camp to exit it and enter the Blood Moor: this area is only populated by, s and s, with no Champion or Unique monsters in Normal. Continue following the path through the wilderness until it forks. If the first fork takes you to the Den, then you may want to use a Scroll of Town Portal to open a portal outside before retracing your steps and taking the second fork to the entrance to the, which is guarded by the redoubtable Rogue, Flavie:

She herself is invulnerable and ignored by any monsters, although no experience is gained from any that she kills for you. You can ignore her warnings as the waypoint for the Cold Plains is just inside by the path: once activated, you can use it to return to the camp's waypoint, then use the portal to the south of the central bonfire to return to the Den.

Den of Evil
If you didn't speak to Akara, this quest is activated upon entering:

If you return to camp to talk to anyone before completing this quest:

The Den is populated by s, s and s accompanied by, who can be raised after death by their Shamans (so make these your priority). Although you'll encounter your first Super Unique monster at the back of the Den, there are no other Champion or Unique monsters here in any difficulty. Your quest log alerts you when you're close to completing this quest:

The last is likely to be your first Super Unique monster...

Corpsefire


Corpsefire will be found at the back of the Den. He and his minions are higher level than other Zombies, giving them greater defense, life, attack rating, damage and experience, but also allowing them to drop higher level items. Corpsefire's Spectral Hit bonus also adds random non-physical damage to his attacks, giving him the ability to poison you, or slow you with cold. When he and every other monster in the Den has been killed, its darkness will be illuminated by streams of light.

If you return to camp via the waypoint just inside the, Flavie's warnings have changed:

If you talk to anyone other than Akara upon your return:

Talk to Akara, and she rewards you with a skill point and gives you the option to reset stat/skill points.

In a game created by someone who's already cleansed the Den of Evil, it's renamed the Cave Level 1 (not to be confused with the in the Cold Plains, which remains a different area).