Endwyr Cadarn is an elf who proclaims the word of Seren outside Tirannwn, acting as an emissary for her. She can be found south of Port Sarim. According to Endwyr, if the player chooses to follow Seren, then she will watch over the player and help provide a sanctuary against the other gods. She will give the player various tasks to complete. Endwyr will also give the player a Banner of Seren and a Book of the Gods. The title "[Name] of Seren" may be obtained from her.
Endwyr's name is derived from Welsh, as are most other elven names. There are multiple possible derivations of her name. In Welsh, "dw yr" refers to water, which seems logical as Endwyr's emissary post is at Port Sarim, a sea port town which is by the water. Also in Welsh, "dwyr" (derived from "noddwyr") refers to a protector, patron, benefactor, or sponsor; this, too, is a plausible translation, as Endwyr promotes the cause of Seren.
During the Song of Seren event, she could also be found south of Burthorpe Castle where she informed players about Desperate Times and the event.