Evasion

Evasion is a passive ability that gives the unit a chance to dodge an incoming physical attack. However, True Strike completely negates all evasion effects, except against towers.

Multiple sources of evasion stack multiplicatively, as well as other sources of miss chance such as Blind effects and the uphill miss chance. While the actual chance to evade is diminishing, each source of evasion increases your effective HP against physical attacks more than the last due to evasion's exponential nature. Note that evasion does not use pseudo-random distribution.

Formula: 
 * Miss chance = (1 - evasion from source 1) x (1 - blind from source 2) ... x (1 - evasion/blind from source n) x uphill miss chance
 * = Πn (1 - evasion/blindn) x uphill miss chance


 * Hit chance = 1 - [(1 - accuracy from source 1) x (1 - true strike from source 2)] = 1 - Πn (1 - accuracy/true striken)


 * Final hit chance = 1 - miss chance + (hit chance * miss chance) = 1 - miss chance x (1 - hit chance)


 * Final miss chance = 1 - final hit chance = miss chance x (1 - hit chance)



I.e. for Butterfly the chance to get hit is 65% because Butterfly has 35% evasion. The source of evasion values must be expressed in hundredths (so if we have 50% evasion, the value needs to be 50/100 = 0.50).

As an example, if Phantom Assassin has Level 4 Blur (0.5 chance to get hit) and Butterfly (0.65 chance to get hit), her chance to get hit by attacks is 0.5 * 0.65 = 0.325 or 32.5%. A more concrete way of thinking about evasion stacking is that for an attack to bypass an evasion stack and connect, it should bypass each source of evasion in sequence. Only if all sources of evasion fail, is the attack able to deal damage.

Evasion
Evasion is a status effect that causes incoming projectiles to miss.

Sources of Evasion

Blind
Blind is a type of status effect that gives the afflicted unit a chance to miss on attack. This effect stacks multiplicatively with evasion, the base 25% chance for ranged heroes to miss when attacking from downhill, and other blind effects.

Sources of Blind

Uphill miss chance
The uphill miss chance is a conditional effect, that causes 25% of the attacks to miss if the attacker is at a lower terrain level as the target. It does not matter how many terrain levels difference is between them, the miss chance stays 25%. The terrain level difference of the attacker and the target is taken into account when the attacker launches its projectile and not when it hits the target. Thus, an attack can still miss due to the uphill miss chance even when both the attacker and the target stand at the same elevation level upon projectile impact.

True Strike
True Stike is an attack modifier that prevents the affected unit's attacks from missing, negating evasion, blindness and the 25% uphill miss chance for ranged units. Though, projectiles of a ranged unit with True Strike can still be disjointed. True Strike does not work when attacking buildings. However, it works against any other unit, including wards and allied units.

Sources of True Strike

Accuracy
Accuracy is a status effect which gives units attacking the affected unit a chance to ignore evasion and blindness. Just like with True Strike, it also works against uphill miss chance and ranged attacks can still be disjointed.

Sources of Accuracy