I really wish I could show it somehow, but for now it's all behind the curtains. All it does is is increases certain variable by one point.About Lymph upgrades, Where can I see what is upgraded? Because i checked every stat after upgrading 3 times and nothing changed

But that variable value counts each time certain spell is casted, here is just a damage formula for a simple Beginner's flame:
</damage formula>
value = 30 + ($gameVariables.value(141)/50) + user.mat + ((30 + ($gameVariables.value(141)/50) + user.mat) * $gameVariables.value(181) * 0.3);
Example: If protagonist is on the fifth level, with a 40 fire exp. MAT is 20 on fifth level. The clean damage is :
Without buff: 30 + (40/50) + 20 + ((30 + 40/50) + 20) * 0 ≈ 51
With three lymph buffs: 30 + (40/50) + 20 + ((30 + 40/50) + 20) * 0.9 ≈ 51 + 46 ≈ 97
I guess it's noticeably.