Nova crystals 2.

"But that brings us to the question, what is the researcher using something that only sucks in mana to do?" Blake's question put everybody into deep thought.

"As it said in the journal, it doesn't go well with organic matter meaning it can't be too close to the user, thereby removing the idea of an equipment..." Brian said.

"Well, that leaves us with the same idea we all have, war." Castiel and Brian nodded to Blake's words.

[According to the journal, it mentioned the nova crystals undergoing multiple tests, meaning they surely have many uses just that we don't know about them.

As for your conjecture, you are right about it being for war. They could be used to make very powerful artifacts with devastating effects that could easily turn the tide of battle.] The system said.