[OP: ]
After their match started, Rein first used her personal (tier-1) water magic and spells that were super easy to prepare and even easier to explode.
They were normal water bubbles with a compressed fog of Mana inside them and when overcharged with more Mana, the bubbles would explode and the energy inside them would release in the form of a shockwave and burst of energy.
And there were many of these bubbles so her opponent, house captain Alpha was surprised. But his senses were sharp enough to pull him out of the area of the explosion and help him move through the safe places without the explosions.
And the reason he was avoiding those explosions wasn't that he can't endure the intensity of those little blasts but the knockback effect of those shockwaves contained within themselves.
If he was caught up in them even a little and lost his footing, he would give a fatal opening to a mage, one with water attribute at her command no less.
