When Arcyu spins rapidly, it generates star-shaped light projectiles all around it as a way of repelling others. If this fails to deter attackers, it follows up with a beam of pure light from its core.
It gathers with others in the night and makes its red core glow on and off with the twinkling stars. It is described in mythology as the Pokémon that shaped the universe with its 1,000 arms.