Overview
Dragonqueen is a Valheim world location that spawns in the mountain biome, identified internally as Dragonqueen. World generation places up to 3 per world, with terrain constraints (max delta 4, max distance 8000, altitude 150-500), and an exclusion radius of 12m, which is why some seeds have far more of them than others. The data tags it as prioritized.
About
Dragonqueen is Moder's Forsaken Altar atop a Mountain peak. Three Dragon eggs gathered from Drake nests are placed on the central stone to summon Valheim's fourth boss.