Becker charges toward Allen and swings his sickle at him, Becker reminds him of Trevor. By the looks of Becker's playstyle which is similar to Trevor's, Allen thinks that he could win against him since he has been watching Trevor all the time on Utube.
Allen tries to dodge but for some reason, Becker's sickle is still heading toward him. Knowing that he can't dodge it, Allen swings his sword to repel the sickle but the force of the sickle is higher than his strength and his hand and sword bounce back. Before he can recover from that, Becker is already swinging his sickle at him again and hitting him in the face.
Allen drinks a lot of potions to recover his HP but that doesn't stop Becker from attacking him. Allen is so confused and irritated that all Becker's attacks always land on him no matter how many times he tried to dodge them.