Also known as the Economizer in the SNES and PlayStation releases, the Celestriad is a relic that reduces the MP cost for all Magic spells, Lore spells, and Esper summons to 1 MP.
An easy way of obtaining multiple Celestriads is to equip Gogo with three Steal abilities, and give him/her the Brigand's Glove and Safety Bit relics. Betting a Murakumo will put the player in a fight against Galypdes, an otherwise rare enemy in the Phoenix Cave. Gogo will repeatedly Mug the Galypdes, stealing either a Phoenix Down, or, if the player is lucky, a Celestriad. Upon winning the fight, the player wins a Holy Lance, which the player can then bet, fighting a Death Machine to obtain a new Murakumo, starting the cycle over again. Another way of obtaining a Celestriad is an item drop from Brachiosaur.