it says that a servant can reach 500% charge on the np gauge if it's at np5 but in the game it can only reach up to 300%, same for a np3 servant it can only reach up to 200% but it says it can reach 300%. so how exactly do NP lvl and charges work?
At np level 2-4 you can reach a maximum overcharge level of 400%. This is done by filling the bar to 200% and then casting the np at the end of a chain of three nps. So basically need the other two servants to have there nps up and cast them before hand. Same logic for np5, get the bar to 300% overcharge then cast it at the end of the chain of nps to have a 500% overcharged np
To add to this, overcharge usually increases the success or the overall affect of additional things that happen with the np. Sometimes like with Hans, it increases the heal over time amount from 1k to 3k. Sometimes it even buffs extra damage, like with Robin Hood it buffs the extra damage his np does if the target was poisoned. Most of the time it just increases the % of the debuffs the np applies on the enemy.
Np level on the other hand increases the damage multiplier of the np. At np 1 you have your base multiplier. At np 2 you get the biggest buff of 200% more (additive) damage added to the multiplier and after that it's 100, 50 and 50 which makes for 400% difference (additive) between np1 and np5
