Diablo II/Den of Evil

The Den of Evil is the first quest received from the exiled Rogues, given to you very shortly after beginning the game from the priestess Akara.

Blood Moor
The Den is located beyond the camp palisades in the Blood Moor, the first region with hostile enemies. The weakest of these enemies are the demons called Fallen, next strongest are the Quill Rats, and Zombies. All enemies in this area are comparatively weak, and can be killed with one or two hits from your starting weapon. To reach the Den, follow the dirt path through the Blood Moor until you reach a cave opening; this is the Den of Evil.

Den of Evil
The objective of this mission is to slay all enemies within the Den. The enemies inside are identical to what you confronted in the Blood Moor, except for a couple important additions. The first is your introduction to the Fallen Shaman, a demon much like the other Fallen except that they attack with a fire bolt which does more damage, and can revive Fallen that you have killed. You can find these enemies in packs with other Fallen. The easiest way to deal with Shamans are to kill them before the other Fallen, so that they don't get the opportunity to bring every Fallen you kill back to life. The second new enemy is the Gargantuan Beast, a towering brute can take more hits than other monsters and deals more melee damage.

Corpsefire
Super Unique Zombie (Spectral Hit)

Eventually, you will encounter your first Super Unique monster, a Zombie named Corpsefire who has more health and deals more damage than other zombies. It will take a few extra hits to kill Corpsefire, but the items dropped are potentially more valuable than other monsters.

When the last monsters have been cleared from the Den, the red glow will disappear and light will flood the cave. When you return to the Rogue Encampment, speak to Akara and she will reward you with an extra skill point.