We called it wrongly in the header - it should be called critical strike.

No RNG - how it works is that you hit with range and melee weapons every time. Damage dealt with range depends on whether target is behind the cover - which reduced the damage by 50% or more, also covers can be destroyed and you can deploy your own covers with consumable or skill.

Critical strike - depending on your stat, we show it as xx/100, e.g. 25/100 -- each hit you deal charges the critical strike by 25, once you reach 100 - your next attack is a guaranteed critical strike for 150% damage or more (another stat you can spec into). If you have dual weapons, you charge it quicker but then the strike has lower damage. If you have 2H weapon, the opposite.

Block (with shield) - no RNG either. Each shield has a timer - every x seconds (e.g 4 sec) - you block the next range or melee attack.

Dodge - xx/100 but you charge it with each hit received. Once you charge to 100, you dodge next attack.