Note
A lot of people were asking why Moises was the key for the unsealing the twelve ancestral spirits.
This is because if you all remember in Chapter 37, the key for unsealing the first 8 was Keita who was also a flame user. After he died, the key for unsealing the twelve ancestral spirits didn't have to be a flame user anymore but someone who was obsessed with nature. That was why Tahara never got the chance to meet the elves in the forest upon arriving to Moises school. The ancestral spirits had already found put their second key and was willing to put it into action.
This was why Moises was used as the second key for unsealing the ancestral spirits.