Frequent Emberai-Abyss Conflict
See 
Scaldmere Culture for details.
The 
Fire magic infused within the 
Emberai drive them to be an active peoples who build pressure. They gather energy through mutual hype and feel alive as the momentum is building. But pressure builds boundaries which they are compelled to burst.
The Abyss Sanctum Culture and Emberai culture generates chronic friction. The Abyss watches, holds, calculates and controls, while Fire moves, acts, declares, and proves. 
Abyss Sanctum governance feels like being suffocated in an alien container. And Fire magic is compelled to burst boundaries.
Then in Scaldmere Culture, their ranked ordings prevent them from using type of work to improve their personal prestige. One’s social standing in the community becomes socially critical, motivating people to move and act in order to gain approval. Activating others through emotion and contribution is rewarded, while somber emotions and lack of enthusiasm are shunned. And shunned people risk demotion, endangerment, and even death through honor killings. The people in therefore Scaldmere cannot express their grief, fear, shame and futility openly, and redirect those emotions towards anger, violence, and collective action.
The Emberai therefore rebel against the Abyss Sanctum regularly, roughly once every hundred years. This becomes their avenue to feel alive, build dignity, strengthen solidarity, and vent frustrations. The act feels cleansing, honorable, and communal.
War of 1103 HC
Abyss Master: 
Mulsae
Damion enters the battle eager for a glorious death, but when he sees how many young soldiers are dying beside him, he realizes that his desire to die well is less important than their chance to live at all. Expecting execution, he orders surrender to save the grunts who can still return to Scaldmere.
War of 986 HC
Abyss Master: Mulsae
After the 
Mutual Sanctum Slaughter, Mulsae is left the only survivor of the Abyss Sanctum ruling family. Since Mulsae is not a full 
Abyss Starborne, and without extra family members backing him up, Scaldmere believes he is weakened and that this is a perfect opportunity to finally break free to independence.
Mulsae personally joins in on the battle to demonstrate that his hybrid state does not weaken him. He is extremely powerful, perhaps more powerful than Mulsae’s Grandfather ever was.
As Mulsae’s personal power becomes undeniable, Scaldmere’s rebellion begins to collapse. Their strongholds fall, their officers die, and the flamekeepers are forced to accept that Mulsae does not need a ruling family behind him to hold the Sanctum. The war ends when the flamekeepers swear formal submission directly to Mulsae as Abyss Master and recognize his rule as legitimate.
Flamekeepers instantly pivot to elevate those who died in the war to glory. The prowess Damion demonstrated is emphasized to encourage fighters to work harder to become like him. If there were only more Damions, perhaps they could have won.
War of 894 HC
Abyss Master: Mulsae’s Grandfather
Some Emberai accept Mulsae as a chance for stability and greater influence within the Abyss Sanctum. Others see him as a manufactured puppet meant to infiltrate and tame Emberai rule from within. Rivalries among flamekeepers deepen the fracture, and the conflict spreads through Scaldmere.
Mulsae’s grandfather won’t escalate into another exterminatory revenge campaign like 761. Instead, once the conflict reaches a certain cost, he withdraws Mulsae from the post and brokers a ceasefire with Scaldmere.
War of 761 HC
Abyss Master: Mulsae’s Grandfather