As per a question I asked, Altair, if he's feeling up to it after that first foray into the subspace, will want to try garbled communicating with the Glatisant... somewhere. He's not totally sold on why it has to be fought. Can't it be banished or dismantled with help from Adversaries or something? Can it be broken up like a volksgeist? Can it be Interfaced? He's got Siren Song of Calming to try on it, but alas he is only one Singer and probably wouldn't be able to fully calm it. He can also use Oracle of Sight powers or even Indigo Color magic to see weak points (for massive damage) but again, he'd have to be convinced fighting is the answer.

If all that's a bust, there's always his Familiar's cryptic warning to unravel, and subspace stuff.