Upgrade is a stat boost that effects the Stat Rate of the character.
Tier I
Doubles the increase of Perma Stats via levelling. Decreases stat gain from Training by 1 point.
Tier II
2.5 times Increase of stats for rebirths. Does not Stack with Tier 1. Decreases stat gain from Training by 1 point.
Tier III
2.5 times Increase of stats for rebirths, Doubles the increase of Perma Stats via levelling, and double experience. Decreases stat gain from Training by 2 points.
Tier IV
3 times Increase of stats for rebirths, Doubles the increase of Perma Stats via levelling, and 2.5x experience. Decreases stat gain from Training by 2 points.