A digital-only Horus Heresy short story by John French, Ordo Sinister is the first Black Library story to feature this particular Titan Legion, who have only recently been explored by Forge World in their book Inferno. Taking place during the Webway War, it sees a single Titan holding back an entire daemonic incursion on its own, for this is no ordinary Titan. Commanded by Prefect Hydragyrum, controlled and powered by…unconventional means, Borealis Thoon is a Psi-Titan.
