Power levels in the world
Beast Rankings
beasts scale from Tier 1 to 100. Tier 1 being compared to an athletic grown man for humans and Tier 100 being comared to a disaster that can obliterate earth with a wave of its hands. Each beast drops beast cores corresponding to their Tier.
beast stones can be harvested and either used to make magic equipment or can be absorbed directly into a person to strengthen someone.
Equipment rankings
equipment goes from grade 0 to grade 10. grade 0 are ordinary equipment without magic and grade 10 are weapons that can basically split planets by default.
human levels
humans have restrictions on their levels with regards to their rank, the ranks are F,E,D,C,B,A and S with each rank raising your potential by 5 levels, from level 0, which is an ordinary person without magic, to level 35, an S-rank esper at maximum strength. the ranks and level basically say a persons minimum Mana capacity and future potential.