Zenis decided to attack Billy because keeping his distance was obviously the worst thing he could do. In the meantime, Billy decided to avoid stealing the enemy's health. He probably had the skill that put him in the over-health status, but any loss would trigger that insane attack again. As much as Billy hated to admit it, he couldn't defeat Zenis as he was now, and he needed more knowledge…
"I need to keep my cool and learn more while stalling for time, and the others will also benefit from this," Billy thought. "Even though he spent a lot of time here, he could only have leveled up a few skills, not all of them."
Zenis fired a massive ball of magic mercury, and Billy managed to block it with a single hand, and then he increased his speed in time to block Zenis' kick. It was a pain to keep Limited Foresight active and fight at the same time, but it was convenient for situations like that.