Evasion

Evasion is one of the three core defences that can be found on equipment. It is associated with dexterity and provides an entropy-based system of damage avoidance against attack projectiles and strikes. It does not protect against area of effect hits by default.

Mechanics

Evading an attack prevents all damage from the attack and other hit-related effects. For projectiles, evasion prevents collision. Chance to evade/chance to hit is determined by a function of the defender's evasion rating against the attacker's accuracy rating. Chance to hit cannot go below 5%; likewise, chance to evade cannot exceed 95%.

Additionally, if the evasion check fails, leading to a hit, and that hit would deal a critical strike, the chance to evade is tested again independently. If this check is passed, the critical strike is downgraded to a non-critical strike.

Entropy

Evasion is not a random system. Instead, it uses a deterministic "entropy" system that ensures a hit will occur after a certain number of evades:

1. If it is the first time an entity is attacked, or if the time since the last attempted hit exceeds 100 server ticks (3.33 seconds), randomize the entropy value from 0-99.
2. Calculate the attacker's chance to hit against the defender's chance to evade, and add this integer to the entropy value.
3. If the resulting entropy value is lower than 100, the hit counts as evade. When the value reaches 100 or greater, the check counts as a hit, and subtract 100 from the entropy value.

The secondary critical strike downgrade test does not affect the entropy value.

Example

A player is fighting three monsters, one (A) with a 70% chance to hit and two (B, C) with a 45% chance to hit.

• A attacks. The player's entropy value is a random number between 0-99, in this case 37.
• A adds 70 to the counter, raising it to 100 or greater, and hits. 100 is subtracted and the entropy is now at 7.
• B attacks, adding 45. 52
• C attacks, adding 45. 97
• A attacks, adding 70. This hits and the entropy becomes 67. It happens to be a critical strike, which means it has a 70% chance to do bonus damage. This roll is independent and doesn't affect entropy.
• The player runs away for >6 seconds, so a new entropy value will be rolled on the next attack.

Template:Cob As a result, if a player has a 1 in N chance to be hit, then the player will be hit exactly once for every N consecutive attacks. This eliminates all possibilities of lucky and/or unlucky streaks. It is still based on chance because of the entropy's value randomization in the first step. Note that if multiple mobs are attacking one character, all of the mobs' attacks share the same entropy value. The chance to evade shown in the character stats window is based on the average accuracy of a monster at the player's level.

Other mechanics

When defending against monster hits, there is no distinction between attacks and spells and will apply to any projectiles or strike attacks from enemies. Area of effect skills cannot be evaded unless Acrobatics is taken.

When attacking monsters, their evasion only provides avoidance against projectile attacks and strikes, interacting with accuracy/chance to hit. Non-attack projectiles such as from spells do not consider evasion.

Bypassing evasion

There are some modifiers which bypass evasion: Cannot Evade enemy Attacks (e.g. the Unwavering Stance keystone), Hits cannot be Evaded, or Always Hits.

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