Similar to the Gargoyles, Triton, Nereid, and Phobos must be eliminated at the same time, as failure to do so will cause them to revive and retort with Delta Attack. The battle can be won easily by using Odin against them. The Magic Lamp can even be recharged nearby.
Like his (her?) companions, Nereid's name comes from Greek mythology. He/she is named after the Nereids, a group of fifty sister sea nymphs. The Nereids were the daughters of the titan Nereus, and are often the companions of the sea god Poseidon.