Dota = Defense of the Ancients. Dota is a multiplayer online battle arena mod for the video game Warcraft III: Reign of Chaos and its expansion, Warcraft III: The Frozen Throne, based on the "Aeon of Strife" map for StarCraft. The objective of the scenario is for each team to destroy the opponents' Ancients, 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. As in role-playing games, players level up their heroes and use gold to buy equipment during the mission
copy paste from Wiki
There is many games like this, some is F2P and some cost a few quid.