Cult of the iron dragon -
After the Great War, several survivors formed a unit and carried out attacks on remaining posts of the Order. They burned down many villages and had no regard for civilians. Ingrimm was unaware of the unit's actions until the situation between the Domination and the Holy Order threatened to escalate again. Inngrim banished the unit from the Domination. The unit moved on, towards Vulcan, where they built a shelter for the time being. When food became scarce, they had to leave the depths of the volcano and went hunting. Seeing the Order in enemy territory, they did not hesitate and immediately attacked without mercy. They overlooked the fact that the soldiers of the Order were on the run, a huge dragon was chasing them. The unit smashed the soldiers of the Order, the dragon landed right in front of the unit of the Domination.
The dragon admired the unit, with what aggressiveness they brandished their weapons. The dragon thanked the unit, the dragon believed that the unit took out the enemy soldiers for the dragon. It was Shaargath, the iron dragon. He breathed fire on the unit and should have burned them alive, but the unit remained completely unharmed. It was a reward from Shaargath, the fire of the iron dragon strengthened the armor and weapons. Their armor turned gray/black and golden. They founded a secret cult to be able to fight the Order from all sides. Shaargath flew over Whitesong and scouted the positions of the order. Shaargath attacked all of the Order's positions and destroyed more than half of the Order's remaining positions. While the unit continued to patrol and attack the soldiers from the ground, Shaargath continued with the air strikes.
The unit swore allegiance to Shaargath and they founded the Cult of the Iron Dragon.
The unit made its way back to Inngrim and presented him with their successes in the fight against the Order. They also brought with them battle plans they found with all the markers where the Order planned to attack. Inngrim was impressed by what they had accomplished in the few months they had been away. Inngrim accepted them back into the Domination and used the Cult of the Iron Dragon for missions he does not want the Domination to be associated with.
You have good ideas, keep it imagining story's.