Team Fortress 2 characters most likely.
DotA 2 will be free to play, but have microtransactions, a la League of Legends
This troper thinks that the DOTA 2 universe, rather than taking place in the Warcraft universe like its predecessor, is actually Valhalla from Norse mythology. The heroes are Earth's greatest warriors and the creeps are lesser warriors who have entered Valhalla, while the neutrals are now eradicated monsters of the world. Everyone is constantly battling to train for the ultimate army, to fight in the battles that will happen when Ragnorok occurs.