Bin-Yakins Seal
Bin-Yakin's Seal is the northernmost of four Child of Jhil caves in the Highlands biome, which include The Scraps, Jhil's Roost, and Lockstone Cave.
The entrance to Bin-Yakin's Seal is marked by a Bonfire on a high ledge, north-east of The Great Dam, and is guarded by Child of Jhil demons. Access to the ledge is via the snow at the east edge of the Highlands. Alternative access is via a hole in the cave ceiling that can be found to the north-east, next to the world border.
There is a Large Chest outside the entrance along the cliff edge.
The nests on the cave floor can be harvested by hand for Feathers.
The cave is the home to several Child of Jhil demons, as well as the boss Feasts-On-Flesh, located in a small pit about halfway into the cave.
Black Blood Pick
Black Blood Hatchet
Black Blood Sickle
Black Blood Skinning Knife
This boss and those in the other caves in this area are also the only sources of Black Blood for crafting the Specialist Ammunition IV arrows.
There is a Legendary Chest located in the chamber just east of Feasts-On-Flesh, with the skylight, sitting partway up the pillar.