The Crystalians are pure-crystal beings, mute and four-limbed, who patrol the deep crystal tunnels under Liurnia, Caelid, and Altus. Their bodies are 'fashioned from pure crystal, a deed impossible for a human,' the Crystal Sword and Crystal Spear descriptions repeat. Their staves enhance Crystalian sorceries, and the Crystal Staff's text records what their interior life is like : 'the Crystalian's faint cogitation is known as the wisdom of stone. This staff can only be wielded by those of intellect high enough to grasp such wisdom.' Slow to think, slower to die, Crystalians do not speak.

Their loyalty has only one object. The Crystal Spear flavour text gives the canon's clearest statement of their purpose : 'The inscrutable Crystalians have but one clear purpose; to safeguard their crystals unto the end. One theory posits that they yearn for the return of their creator who will carve for them new brethren.' Whoever made the Crystalians is gone. They guard the unsold inventory of an old workshop, hoping the master will return. The Rotten Crystalians of Sellia and Aeonia, infected by Malenia's bloom, are the canon's small tragedy : the wisdom of stone festering, still on watch, still waiting.