MasteryG 20

This could technically be missed if you upgraded every ability to IV and stopped there, since there is a level cap. With only 1 point per level, you would not have enough points to get any ability to level V if you upgrades every ability evenly. That being said, the level V upgrades are often very strong, and every character has at least 1 ability that isn't worth upgrading, so it's extremely unlikely that you would ever actually miss this.