2. Game says block chance reducing to posibility of taking crit and reducing to extra damage when you take crit damage. But what are the rates for this two?

3. How math works with damage reduction buffs?If +25% is it work like 50+(50*25/100) or 50+25?

2. Block chance and damage are inverses of each other, so 33% Block chance will lower the enemies Critcal damage by 33%. For the Block chance and Critcal chance relation I'm not entirely sure but I think it's roughly about for every 3% block chance the enemies CC falls by 1% (or 0.33% CC for every 1% BC). As for how it's calculated wether an enemy blocks or you Crit is as follows:

The game will do it's calculations to determine the attackers CC then 'roll' to see wether you land a Crit or a normal attack. If it rolls a Crit then you Crit, if not then it'll 'roll' for the defender after checking their Block chance. If they block then they of course Block, if not then it's just a regular attack. Pretty simple system basically, if your having trouble visualizing it then just imagine it as a pie graph with only two sections in both scenarios, and that it spins on that to determine what happens, just that the one only spins sometimes.

I specialized in Crit teams for a long time and learned this after facing heavy block chance teams, despite the fact that the enemy would have over 100% block chance I could still Crit them because of this.

3. Everything in this game is addictive as far as I know, so it only just adds/subtracts the percentages like they were whole numbers. Ex if you have Erise and Clara on the same team it would be: 52% (Erise DRB) + 30% (Erise passive) + 25% (Clara passive) = 107% DRB in total (but the game will only count up to 90% in total)

If you have other questions feel free to ask. My friends often call me a wiki about this game lol.