In the years that Cairo spent on the 51st floor, he already learned what he should do to clear this floor. It was actually pretty simple. All he needs to do is to kill the magic beasts inside and absorb the mysterious motes of energy from the corpses
Aside from the corpses, there were also some challenges that he needs to accomplish to be rewarded with more of those energies. As long as no corridor or room was left untouched, Cairo will be able to conquer this floor
However, no matter how many monsters Cairo killed, the energy he had filled in the tattoo of the Tower still looks far less than a drop of water in an ocean
Even if Cairo managed to absorb all the energy from this floor it would still be far from enough. He can only guess that he would be able to fill it on the higher floors. That must be the only way