Demon attack.

If you're reworking the map, it might be worthwhile to make the "rebel town" the same Faction as the one the player chose, and make capturing it a mandatory condition. Then, finding the "Friend" and the Tear of Ashi would become useful. Until the rebels are defeated, the path to the green demon-worshippers could be blocked by a guard post or something similar, so that enemies can sneak through, but the player can't. And don't give the quest right away. For example, first, have the player defeat the bandits. After defeating them, they receive a bonus and the ability to cross the bridge to the rebels. After defeating the rebels, the path to the demon-worshippers opens; their town could potentially be destroyed. After that, the path to Sanctuary can be opened. It would be better to make the demon-worshippers human, red-skinned – Alrik and others – and make them immediately upgraded. And the ending isn't very satisfying; you defeat everyone, and then... nothing. Maybe you could do something like this: after defeating the Demon Lord, a quest appears: "enter Sanctuary and free the enchanted Isabelle." The player runs there, meets Biara with an army and an artifact, defeats her, and she, the nasty thing, sneeringly laughs and says: "While searching for what belongs to others, you lose what is your own." I lured you out, and Armageddon has fallen upon your cities because you touched the artifact. The cities perish, all the player's heroes perish too, and he himself falls somewhere... but that's if there's a sequel.