Supplicants are available in Co-op Missions when playing as Alarak. They are produced in pairs, in a manner similar to zerglings. They automatically sacrifice themselves to keep Alarak alive when in close proximity to him. They can also be sacrificed to fully restore the energy of an ascendant.
While numerically superior, supplicants are very poor units offensively, dealing little damaging and having short range. There is little point to producing supplicants if the player is not using Alarak or ascendants much.