Range
The Devourer's effective range extends far beyond direct physical attacks. Its corruption spread across forests, rivers, roads, villages, and entire regions surrounding its location. The effects of its presence were felt across much of Valenor long before it physically arrived.
Durability
The Devourer repeatedly survived siege weapons, massed military attacks, ballista fire, powerful magical attacks, and direct combat with some of the strongest individuals in the kingdom. Damage that would destroy normal creatures was quickly repaired through its regenerative biomass.
Speed
The creature is fast enough to overwhelm trained soldiers before they can properly react, rapidly cross battlefields, and break through military formations. Despite its large size, it consistently moved faster than medieval armies could respond.
Intelligence
While initially behaving like a savage monster, the Devourer gradually demonstrated strategic thinking. It cut off retreat routes, trapped armies, targeted important locations, adapted during battle, and deliberately used forms and appearances that would cause greater fear among its enemies.
Overall Tier
Based purely on the events of the story, the Devourer would most reasonably be viewed as a large-scale kingdom-ending threat, capable of destroying major cities, military strongholds, and eventually collapsing an entire nation through direct overwhelming superiority.