Dimension magic.

"From your looks, it seems like you have figured out the purpose of the exercise. Just remain and silent and continue the process, others still need to find this for themselves." Zirrack appeared in front of Blake and spoke without any other person noticing.

After 20 minutes of waiting, most of the class had noticed the reduction and absorption of the mana by the body. So Zirrack rewarded them with points before explaining to the few who weren't able to detect the change.

"Now that is out of the way, let me explain the aim of what you just did." Zirrack said as he paced around the training ground. "When mana continuously circulates back and forth over a long period of time, the body prevents the pathway from getting sore by absorbing part of the energy with each cycle."