Alternatively, perhaps Thordan was meant to be the primal to go along with their Umbral/Light-based calamity in the making, and so he was supposed to go and snack on the Warring Triad. But then we killed Igeyorhm, got Lahabrea eaten, and dealt with Thordan so handily that his summoner scared himself to death at the mere sight of us. That left the Ascians with three primals that could undermine their plans if any one of them survived, which led to Unukalhai being used to get us to do the Ascians' cleanup work for them.