Have at you

Rain and Elisabetha's Wrath converged together as the shadow took over his body and the giant earth's arms turned obsidian. In the next moment, he jumped, he kicked the ceiling, and then fell like a meteor on the ground and punched it with all his might. Immediately, a hole was formed, and Rain could see the cave below… but no signs of the demon king.

"This attack pierced the robot master base, and I just pierced a couple of meters in the cave…" Rain grunted.

Rain repeated the same motion several times and created a bunch of holes in the caves. At least they weren't repairing themselves, so Rain knew the way out. Unlike the robot master, who used a bunch of his mana to constantly repair his base, the demon king decided to use his resources completely for defense and nothing else.