Defense of the Ancients (often referred to as DotA) is a custom scenario for Warcraft III: The Frozen Throne, based on the "Aeon of Strife" map for StarCraft. The objective of the scenario is to destroy the opponents' "Ancient". The two teams' ancients are heavily guarded structures at opposing corners of the map. Players use powerful units known as heroes, and are assisted by allied heroes and AI-controlled fighters called "creeps". As in role-playing games, players level up their hero and use gold to buy equipment during the mission.