Baldur's Gate: Dark Alliance/Crypt

Karne walks into a throne room and stands on an eye. A mysterious voice asks if he has done his job, and then describes the importance of the orb that Karne sent to deliver to the crypt. Lord Xantam requests that Ethon be brought to him, but Karne says his men haven't reported back to him, nervous that someone may have interfered.
 * Karne and Lord Xantam cutscene #1

Entrance
Right when you appear, two skeletons and a zombie will begin attacking you. These undead are much stronger than the kobolds you used to face. Zombies are a special enemy because they can be destroyed in different ways. This is a random effect, but sometimes you can get lucky. If you happen to knock of a zombie's head, it will run around and not attack you. If you cut it in half, sometimes the top half will continue to crawl after you.

Go through the first door and kill the two zombies and four skeletons. Hop over the boxes to reach Fayed, a priest of Ilmater. He will tell you that the living dead began to appear after he found the orb in the Chamber of Ashes. He then barricaded the door to the orb, hoping it would stop them. However, the power of the orb extends beyond walls. Regardless what you say, he will remain in the crypts. Although he won't accompany you, he will provide you with free healing if you want it and also give you the ?? quest.

Continue onwards through the undead, and eventually you'll come to a large room with skeleton archers. They act like the kobolds, but stand in place and have better accuracy. You should be about level 4 after this room.

Head through a door and into a large room. You can go east for treasure, or west to get things done. Head west, then turn north when you reach the save pedestal in the middle, and head down the hallway to the back of a long room. You'll find a treasure chest and Ipswitch's medallion laying on a tomb. Return to the save pedestal and head south to retrieve more treasure. Return, then head west and clear the room of various undead. You can now exit to town via the stairs to open the door to the crypts.

Go back to the Elf Song and return the medallion. Only do this if you need to clear up room in your inventory, or if you need a good melee weapon.

Speak with Ipswitch to complete Family Heirloom and acquire: The mace is good because it has a fast attack speed, medium range, average damage at this point, and an awesome special ability that instantly vaporizes an enemy (this happens randomly when you hit an enemy).
 * A magic mace (Lt. Mace of Disruption +1, about 2-7 damage).
 * 300 experience.

Push the three vases into place. Green goes on the left, blue in the middle, and yellow on the right (they will make a sound when in place). The metal plate on the floor will slide open, and Crypt Level 2 will be open.

Crypt Level 2
From the entrance there will be three zombies and a save pedestal. Head down the hallway and around the bend. You'll come to an intersection. The left and right are extra, and straight ahead is the final room before the hallway to the boss.

In the large room, all of the enemies are hidden in groups. Slowly move around the room until a few appear, then kill them, then move on. The treasure chest in the middle of the back wall (by the save pedestal) contains the Morning Star of Disruption +1 (9-13 damage), which should be the best melee item in the game at this point (lower maximum damage than a 2 hander or the flaming long sword, but faster, 1h, and with disruption).

Take both paths past here to kill lots of undead, and then you'll reach the final save pedestal before the boss. Save, and when ready, head down the stairs (either door) into the boss room.

Boss
The Orb of the Undead will sit on its pedestal and power up. Attack it as much as you can right now, because it will retreat into the air after about 5-10 seconds. When this happens, it will summon a lot of undead that you have to kill before it will come down to its pedestal again. Take care of the undead (watch your health), but before killing the last one, lead it back to the pedestal so you don't miss the orb when its weak. Kill the undead when you're close, then prepare to kill the orb. On normal, this should take about 2-4 times (including the first freebie). On easy mode, it has about 300 health, which takes about 1-3 times (including the first freebie). When it dies, energy or spirits will burst out of it until it shatters in an explosion of light.

Fayed will meet you after the fight. You find a map on Keissen's body, which tells you and him that the orb was placed there on purpose. Fayed tells you he will consult the remaining priests who will send word to you at the when they have a plan, and then he gives you a token of appreciation. You complete the ?? quest, with the reward of:
 * An amulet of protection (+2 armor).
 * 750 experience.

Recall to the Elf Song, then speak with Osala to finish the Find Keissen quest and acquire:
 * A ring of protection (+1 armor).
 * 750 experience.

There are now two new patrons. One stands beside Ethon, and the other, Keaira, sits in the back. Speak with Keaira to receive the Lost Spice quest. Speak with Jherek, the man next to Ethon. He is from the Harpers, whom Ethon is a member, who wish to recruit you in protecting Baldur's Gate from people like those who planted the Orb of the Undead. You now have a choice: work with the Harpers, or go alone. If you say yes, you will receive the Thieves' Guild quest and a key to the new thieves' guild's entrance.

Back to the sewers
Exit to town, then walk over to the sewers and go in to Sewers Level 1. Head east down the passage to the end, then walk over to the tiny tunnel on the map and enter the Thieves' Guild.