The Dalki's goal
It was impossible to tell with some creatures what tier or level a beast was. The most accurate way would be for someone to look at the crystal. When looking at a beast, most people had to simply guess.
Although this could lead to mistakes on the battlefield. For instance, there could be an advanced tier beast that was the size of someone's head. Although a creature that size may look harmless, it may have a feature or such that would make it deadly.
For Leo, it was a bit easier since he had his aura detecting ability. It would allow him to see the strength of such a thing. What Leo didn't realise, was until he was stood in front of such a creature, was the several galthrium made doors throughout the facility must have had some type of suppressive ability. For until this point, standing in front of the large beast, he had no clue what level of beast he was about to meet.