Billy didn't try to hold back on the use of mana. He only had a small percentage left, so he went and used the full potential of Light Speed Sword. In the end, he regretted it since he ended up hitting the monster's head, and his glaive pierced the monster's chin. However, the impact pushed the monster and Billy to the ceiling above them. Not only did Billy feel like he had hit a concrete wall at five hundred kilometers per hour, but his moving speed made even the small particles of dust pierce his body and eat away his flesh. The friction made his skin begin to burn, and his sweat alone made him feel like someone was pouring boiling oil on him.
"Fucking hell…" Billy thought.