To get to the Flayer Dungeon in Diablo 2: Resurrected, you’ll likely have to make your way through much of the jungle until you find the Flayer Village where the Gidbinn is located. The entrance to the Flayer Dungeon is always close to the Gidbinn.
You have to go to the Flayer Dungeon to find Khalim’s brain for the Khalim’s Will quest, but finding the Flayer Dungeon in the first place isn’t that easy. This is because it is in the Flaying Jungle. And the Jungle Flayer, like all of the Act III jungle areas, is large and very difficult to navigate. It is very easy to spend a lot of time following the wrong path completely, or to find yourself in a completely different area without even realizing it.
Related: How to get to the Halls of Pain in Diablo 2: Risen
From the Spider Forest, explore until you find the Great Swamp. The Flayer Jungle is usually found on the other side of the large spider forest swamp. Once you enter the Flaying Jungle, keep a constant eye on your minimap. Looking for a semi-ruined village with a unique marker somewhere in the middle of it. The unique marker is a small drop with two horns protruding from the top and represents the altar on which Gidbinn can be found. Once you find this, search nearby and you will find the stairs to the Flayer Dungeon. Also keep an eye out for the zone name in the upper right corner of the screen. If he doesn’t say Flayer Jungle, then you’ve gone too far in the wrong direction, then come back immediately.