Zach wasn't the only one who had another go at Monolith. But all of them were completely useless. They didn't so much as touch a hair on his bald head.
After taking a day to reassess, rest, and regroup, the students tried to keep him busy and let someone try and sneak into the Underworld. It didn't work. No matter what setup or strategy they employed, it was all useless before Monolith's overwhelming strength.
The students were faced with a wall they could neither climb nor go around.
With no other options, they could only start building ladders, grapples, drills, or whatever else they could use to get them to the other side of the wall.
For some, that meant polishing their swordwork. For others, it meant training their skills. Some built muscle and physical strength. Some started working on energy.
All of them had ways they could get stronger. But getting stronger was a gradual process that required repetition and refinement. It took time.