Overview
GoblinKing is a Valheim world location that spawns in the plains biome, identified internally as GoblinKing. World generation places up to 4 per world, with terrain constraints (max delta 4), and an exclusion radius of 32m, which is why some seeds have far more of them than others. The data tags it as prioritized.
About
GoblinKing is Yagluth's Forsaken Altar in the Plains. Five Fuling totems looted from Fuling shamans are placed on the central stone to summon Valheim's fifth boss.