Every 100 points of mastery you unlock a new tier and get 1 perk point. You use perk points to unlock the skills in each tier.

[quote=OP]Class Mastery Level: 0 - 600 [Please, don't let this get after 200. This is designed to be something hard to raise. For every 100 you get a perk point and access the new tier, which you can spend in sub-tiers for new abilities. Class Mastery advances as you use abilities. I will inform you every time you reach the next 100. Perk points can be obtained from other events and even from sub-boss monsters.][/quote] 

At least I think that's what was hashed out in the OOC.

Edit : And [b]I think[/b] Shiho raised the limit of class mastery for new characters from 200 to 300, but no way am I going to look for where she said that in the OOC.