Ivaylo nevertheless defeats a larger imperial relief force in the battle of Devina and another numbering five thousand in the Balkan passes.

Despairing of relief, Ivan Asen III flees Tarnovo in 1280, while his brother-in-law George Terter I seizes the throne.

The new ruler temporarily unites the factious aristocracy, and Ivaylo gradually loses support.

He travels in 1280 or 1281 to the Mongol chieftain Nogai Khan, accepting his overlordship and seeking his support to recover his throne.

Nogai is simultaneously approached by Ivaylo's rival Ivan Asen III, who is seeking his own restoration.

Eventually Nogai has Ivaylo murdered, preferring the claim of Ivan Asen III, who is his brother-in-law (both Nogai and Ivan Asen III are married to daughters of Emperor Michael VIII.