When conquering Hirana Monastery, does the buff that needs to be spent have to be from that battlefield, or can it be from a unit in base or on a different battlefield?

Ruling: Any buff on your board can be spent to conquer Hirana Monastery, regardless of whether it is on a unit in your base or on a different battlefield.

Nuances:

• The buff does not need to be specifically from the Hirana Monastery battlefield itself