Archaens or Astrals are the summons in Final Fantasy XV. They are physical manifestations of the power of stars and can be summoned by Noctis to protect the land of Eos. They are linked with the creation of the world and to the main deities. They are intelligent beings with their own predilections and language.
Archaens are classified by size, and Noctis must typically defeat them in battle to obtain them for summoning use. Defeating one in battle earns Noctis special rewards. Once obtained, they can be summoned in battle, except for in tight or enclosed places. They behave based on the situation and where they are summoned. Some attack oppenents, while others provide more supportive roles.