Amayon's return portal can replace its depleted fuel only with souls of the same category that originally triggered Demon Eviction.
The quest rejects arbitrary remaining souls as fuel. The world must be repopulated with the same type—the same metaphorical flavor—that initiated the demon event.
Donut immediately understands what Carl is considering. The necessary summon is not currently in her hand, but she confirms Midnight Express is available to move Carl toward the source once it is drawn.
An empty portal reservoir accepting only one matching soul silhouette while rejecting others.
The restriction points Carl toward recreating a previously removed population rather than harvesting ordinary survivors.