The megadragon king was the leader of the megadragons, a mighty species of Dragons from Axeoth. He dwelt in a vale in the Rusted Desert. During the events of Heroes of Might and Magic IV: Winds of War, he was paid by Spazz Maticus to aid him in his conquests.
The Megadragon King's cave appears as a quest hut in Rusted Desert, the second scenario of the To Rule the World campaign. The cave is located in the southeastern corner of the map, and fulfilling its quest is the scenario's objective. The Megadragon King asks for 100 sulfur and the Dragon Scale Armor and Dragon Scale Shield artifacts, in return for lending Spazz some of his megadragons. In order to obtain the two artifacts, the player must attack the red player and retrieve them from its heroes.
In the subsequent missions featuring Spazz, he will periodically receive megadragons.