Here you can you choose one of the available races (or a random race).

Alliance of Benders - A mighty race that allows you to spawn elemantal units like water or ocean elementals, phoenixes, stone golems, etc.

Ancients - This race is composed of extremly mighty tank units that are expensive but strong.

Burning Legion - Very expensive and slow-spawning units. But all of them have chaos damage which gives them an important advantage when facing divin-armor units.

Humans - The standard race of all AoS games. Quite balanced.

Engines - The mechanical race. All of their units are mechanical type units, which makes them unvulnerable against a lot of organic based spells. Most of them have less hitpoints but divin armor.

Naga - With the humans the second standard race. Quite balanced but at the middle game kind of strong thanks to their lord of the tides.

Skeletons - The rushing race. Some of their units spawn in double-teams. They have less lifepoints but in mass, especially during the eraly game, they are really strong.