Sigendil glimmers bright as the Extremis Chamber plunges into the fray. Mounted upon the noble scions of Dracothion, they are all but unstoppable. First to hit home is the Lightning Echelon; protected by a shimmering field of energy, its line-breaker assault crashes home with battering-ram force. In their wake is the Thunderwave Echelon, despatching the survivors with devastating efficiency as the Lord-Celestant and those of the Drakesworn Temple tear apart the most monstrous foes with sigmarite blade, Stardrake claw, and blasts of celestial force.
Borne by the High Star: The forces of the Extremis Chamber share a close kinship with Dracothion and other celestial beings.
At the start of your first hero phase, you can transport all reserve units from this battalion that are in the Celestial Realm to the battlefield. If you do so, pick a point on the battlefield and set up the units wholly within 24" of that point and more than 9" from any enemy units. Those units cannot move in the following movement phase. After setting up those units, roll a dice for each enemy unit within 18" of the point you picked. On a 4+ that unit suffers D3 mortal wounds.