Ob Nixilis followed Nissa to the Khalni Heart and understood what the hedron network could give him. His spark had been trapped on Zendikar long before, and the defenders’ concentrated mana offered a route back to the Multiverse. Their emergency was, to him, an opportunity to recover freedom and punish the plane.
He broke the alignment, drew power into himself and reignited his spark. Ulamog escaped. Worse, Ob Nixilis summoned Kozilek from beneath Zendikar, turning a fragile containment battle into a confrontation with two titans. Kiora’s confidence and the army’s momentum collapsed under the change.
Gideon, Jace and Nissa were captured and tortured after trying to oppose him. Chandra arrived from Regatha after reconsidering her decision to stay away, and her intervention freed them. The rescue did not restore the trap or the lost army. It gave four exhausted planeswalkers enough time to decide what they were willing to promise.