Whether monsters or Phantoms, they could spend years or even decades advancing from one level to the next, or even taking just a single step to the next stage within a level.
However, this wasn't an ironclad rule, but merely a statistical trend. The stronger a monster or Phantom became, the harder it was to evolve further. The conditions for Phantoms became more dangerous, and the energy barriers for monsters grew to terrifying sizes and strengths.
This trend never stopped and seemed to stretch toward infinity.
Perhaps the end of the path was the peak of energy created by the First Star and Last Star upon collision, but this was nothing more than a theory.
Thus, when a human or monster reached a great lifespan and a respectable level of power, only a few of them attempted to increase their strength at the same rapid pace as before.
Most gave up.
