The place where Kolhdre was planning to intercept Mio was in one of the biggest bases he had. This base was created to research various types of magic that used elvin babies and children as sacrifices to increase the power of a spell. Babies were pure beings with no impurities and they all had an immense amount of untapped potential. For that reason, children were very good catalysts for powerful forbidden spells.
So to protect such an important base, Kolhdre had spent a lot of money to engrave a legendary formation here. This formation took a total of one hundred and twenty years to be completed and it used souls of pure babies as fuel. Those souls were already trapped here.
