Pit of the Faithless Overview - Baldur's Gate 2
The Pit of the Faithless is a zone that you will be visiting during the Investigate and Destroy the Cult of the Eyeless side quest which begins in the Temple District of Athkatla. In order to gain access to this zone you will have to agree to help Gaal during this quest and find the first Rift Device Part. Refusing to help Gaal or attacking him before you progress far enough along in this quest will permanently prevent access to this zone.
Lower level players should be especially careful while exploring this zone since it has many Beholder enemies throughout. For those of you who need help with strategies for Beholder enemies check out my BG2 Beginner's Guide or my How to easily defeat Beholder enemies Youtube Video.
Priests: At this location you'll find a group of priests just chillin' waiting for someone to swing by and take them all out. If you want to make this fight as trivial as can be I recommend shooting a few Fireballs or Skull Traps into the middle of this area. Depending on the difficulty you're playing on and/or how many spells you use - you may be able to take out this entire group from a distance without taking any damage!
Dragon's Bane +3: This is the only magical item in this entire zone that is worth pointing out... and it's not even that great of a magical item to boot. Dragon's Blade +3
Rift Device Part: During the Investigate and Destroy the Cult of the Eyeless side quest you will have to collect this Rift Device Part. Collecting this item will summon the Unseeing Eye which is an Elder Orb Beholder that you'll have to defeat.