A Hydra

His knights' last struggle surprised Arthur as if they had noticed that Veran's attacks were the most effective against his barrier. Then, after Ma made sure that no one was watching, his knights attacked together for the first time.

The waves knight raised her arms and struck the ground, throwing a giant wave toward Arthur. As he split the attack quickly, the big man descended from above, clapping his hands together to raise the ground into attacking him.

The Mad Prince and Kaza each took a side to attack from simultaneously. Arthur threw his barrier to push all of them back. As he was distracted by their final attacks, he spotted something above him.

The winged demi hugged Veran, flying him into the air. It seems that these knights have realized Arthur could only use the barrier or his spiritual energy to block their attacks, so they chose to reveal an opening using that limitation.