The name of that student is Kenny. She is Tina's friend and a water element user. The moment gave them the signal, Kenny immediately attacked using water spears.
You might think that she has the same attack style as Tina's opponent. But her attack style is completely different.
Not only does she attack her opponent using those water Spears, but at the same time, she immediately attacks by creating water balls.
Don't underestimate those water balls as the density of those water balls is high, and those water balls are as strong as steel or even stronger than that.
Also, Sam can easily tell the main purpose of those water balls is not to defeat her opponent.
On the other hand, her opponent is a spear user who has already begun to counterattack. One after another he began to destroy those incoming attacks.