Aritfact drop location
Advent Bay
Pale rider - Mylen's artifact
Cherubim - Melodiana's artifact
Seraphim - Evelyn's artifact
Ophanim - Asmodeus's artifact
Ascended One - Crayl's artifact

Mirage Forest
Daitengu - Rags's artifact
Jormungand - Aht's artifact
Bahamut - Roka's artifact
Fafnir - Crayanne's artifact
Erdgeist - Selvari's artifact

Phema Sluicegate
Abyssal Terror - Paraskevas's artifact
Garuda - Gaptahl's artifact
Devilfish - Anastasia's artifact
Quetzalcoatl - Kohakuren's artifact
Lenia Vea - Suina artifact

Phema Mountains
Razorwing - Phinilly's artifact
Thunder Wyrm - Emelita's artifact
Freki - Uya's artifact
Siren - Eliza's artifact

Valkyrie Falls
Gigas - Yuela's artifact
Orc - Wil's artifact
Drakaina - Lyphia's artifact
Norn - Ms. Eukleia
Idsi - B.Eushully
Valkyrie - W.Eushully

Hannah's artifact is crafted
Lily's artifact is in a chest where Slime Princess was (requires you to finish Advent Bay once)