Perkins was talking about the 9 Hells...
Some of those arms appear to be in shackles, not bracelets. Maybe a revolt in the Hells? The Lords of the 9 diverting the denizens of the abyss to attack the Higher Planes? Could this just be an Eladrin Vengeance Paladin going ham on her Dark Seldarine and Formorian foes? I like any of the options, but this would tie back to Mordies Tome of Foes if it were planar, just as Waterdeep tied back to Xanathar's.