My assumptions watching the RAW:- Johan, the genius dude who helped invent the Reiji Maigo, worked out a counter for Sabrac's Stigma after he was ambushed by Sabrac that one time like a thousand years ago.
- Yuji figured out that Sabrac hid the majority of his existence in the ground, where he could draw it out to revive his fighting form.
- Yuji distributed the antidote which Wilhelmina was holding in reserve. Shana and Margery were back in the fight, and Sabrac didn't know they were acting until it was too late for him to run away.
- Margery cast her big hax spell, breaking Sabrac's regeneration matrix thingy. Shana kills him with fire.
- Shana ALMOST confesses to Yuji.