Romustion is experimenting with the transformation formula for eternal life, since Spirit of Fire that he summoned is fading away. Collect Soul Vigor and bring it to him.
Step 1. Collect Soul Vigor: You can sometimes obtain Soul Vigor after defeating monsters in Atreia during the event period. Alchemists use this material. and take it to RomustionA High Alchemist visiting Pernon. He has remarkable abilities and created the great spirit of fire through the alchemy of soul, a taboo in world of alchemy. However, the life of the great spirit is lost.. (You need to collect: [Event] Soul Vigor)