Defense of the Ancients (DotA) is a multiplayer online battle arena (MOBA) mod for the video game Warcraft III: Reign of Chaos (2002) and its expansion, The Frozen Throne (2003). The objective of the game is for each team to destroy their opponents' Ancient, a heavily guarded structure at the opposing corner of the map. Players use powerful units known as heroes, and are assisted by allied teammates and AI-controlled fighters. As in role-playing games, players level up their heroes and use gold to buy equipment during the game.