Who is Loken in World of Warcraft

Prime Designate Loken was one of the servants of the Titans, and was appointed overseer of Ulduar (and by extension, the state of Azeroth) along with the Keepers Hodir, Freya, Thorim and Mimiron.

However, during the long time of keeping watch over the prison of Yogg-Saron, Loken became somehow corrupted, and enslaved the keepers to his will. Thorim left Ulduar as there was an uprising between Frost and Storm giants, so he was not immediately enslaved.

Only after the players stir him from his apathy, and starts to interfere, Loken captures him and places him on guard in Ulduar, with the illusion of Sif to keep him under Yogg-Saron's control.

He himself retreated into the Halls of Lightning, to further his designs, where a group of heroes terminates him. The resulting instability, together with that of the release of Yogg-Saron, triggers the activation of Algalon. Algalon arrives to scan the planet for systemic corruption, deciding whether to leave it as is or call the Titans to have the planet re-originated.