Bloodlust

A Monster Vulnerability.
From the Book of Engoku:

Description

Monsters with this vulnerability lose all control once engaged in combat and are unable to retreat until all enemies are dead or it is slain in battle. Some creatures have a more limited version of this vulnerability, and are only forced to continue fighting against particular types of enemy. See the individual descriptions for further information.

Bloodthirsty Beasties (partial list)

• Black Dog
• Garuda (vs. any sort of Dragon or snake only)
• Naga (vs. Garudas)