Selkis, the Obstructor
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Selkis, the Obstructor is a massive Dusk Servitor that appears in the Chances and Choices World Quest mission. Selkis acts as a obstruction against the Guardians to prevent them from reaching the Titan rig reactor core which Mithrax, the Forsaken is also trying to gain control. Selkis might be the High Servitor for Mithrax.
List of appearances