Eiren is an Ace hero sealed deep inside a dungeon... Only you can sense her presence, because like her, you may live with a dormant Sluagh spirit inside. But your Sluagh will awaken if you feed it Dorcha, the darkness you can leech from the souls of your enemies with your powerful new Chain Blade. After you release Eiren, search for clues to the secret of Bachram. You might even learn something about what the Fomors are up to. After all, there must be a reason why they tried to snatch Eiren’s power away from her...
A woman is standing in front of me, her features sharp and aquiline. Silky, golden hair flows behind her, and her arms are crossed. She looks confident, almost noble. She has one turquoise eye and one violet eye, each with the same lively sparkle in their depths
Born as a half-Fomor, Eiren possessed a parasite known as the Sluagh that would empower her abilities, but absorbed the negative energy of Dorcha from her slain enemies and eventually spiral out of control, forcing her to attack her closest comrades. Horrified, Eiren tried to find ways to keep the Sluagh under control and ultimately concludes that she must seal herself. Refusing to accept her fate, the other Aces have been searching for a way to unseal her; meanwhile the Fomors that have coveted her power are secretly working behind the scenes.
- The rune displayed on her outfit is the same as Merlin's Runestone, and it is an actual Anglo-Saxon rune: ᛄ
- Possessed Eiren is known on the Korean server as "이스시에 잠식된 에아렌" or "Eiren encroached by Aos Sí/Aes Sídhe"; most if not all references to the Slaugh are instead Aos Sí.
- While Aos Sí/Aes Sídhe (Fairy Folk) refers to fairies in a general sense, the Slua Sí/Sluagh Sídhe (Host Fairies) are more commonly evil.