Description^{?}  

0.5% chance per rank when hit that the damage dealt will be reduced to 1. Does not stack with the equivalent Warpriest effect. This perk has an increased chance to activate on level 20 items.  
Release date  25 January 2016 (Update) 
Gizmo type  Armour 
Maximum rank  5 
Lucky is an Invention perk which has a 0.5% chance per rank when hit that the damage dealt will be reduced to 1. It can be created in armour gizmos.
This perk does not stack with Saradomin or Zamorak warpriest armour. Lucky works on all damage types, including typeless damage taken in combat. This means that it works on reflected damage and Helwyr's bleeds, but does not activate for Araxxor's cleave or when trying to eat a dwarven rock cake (cooled).^{[source needed]}
When the perk triggers, it prompts the following message with X replaced by the reduction: Your Lucky perk reduces the damage of this attack by X.
Rank  Activation chance  Average damage reduction 

1  0.5% (0.55%)  0.5% (0.55%) 
2  1.0% (1.10%)  1.0% (1.10%) 
3  1.5% (1.65%)  1.5% (1.65%) 
4  2.0% (2.20%)  2.0% (2.20%) 
5  2.5% (2.75%)  2.5% (2.75%) 
 All numbers in parentheses refer to level 20 gear.
Given a monster's minimum and maximum hits , and the rank of lucky , the average damage reduction of the perk over hits can be calculated approximately as:
Calculations
 The average ratio of damage taken, , from Lucky to that of without Lucky is
 The average damage reduction is then, after some rearranging,
 Notes
 A calculator for this is at the top of this page.
 Assumption :
 All hits that are taken have the possibility to proc Lucky.
 is the rank of the Lucky perk.
 is the proc chance of Lucky to activate (if the perk is on level 20 gear, then this value is multiplied by 1.1).
 when or . This represents summing over all possibilities where integer represents the amount of hits prior to the proc of Lucky. The probability of Lucky proccing on hit is therefore .
 is the random value uniformly sampled between the enemy's minimum hit and maximum hit. The describes different sets of hits. The sets are regenerated for every new value of .
 has elements with integer . This is the damage taken before the perk procs.
 Clarification : This does mean that for that there are no elements in this set.
 is the damage taken from a single hit if the Lucky perk were to proc (without having it on gear).
 The set of values in for integer is the same in both the numerator and denominator of the ratios for any given .
 has elements with integer . This is the damage taken before the perk procs.
 Simplifications
 This can be simplified if the assumption is that every value integer , integer is taken to be the same . In this scenario, there is no random element and the above is then only dependent on the proc chance. A table is provided at the top of the page.
Using these simplifications, the damage reduction reduces to
Sources
Material  Rarity  Perk ranks with X materials  

1  2  3  4  5  
Silent components  Rare  1  2  3  4–5  5  
Delicate parts  Common  0  0  1  1–2  1–2  
Light components  Uncommon  0  1–2  1–2  1–3  1–5  
Fortunate components  Rare  1  1–2  1–3  1–5  1–5 
Suggested gizmos
Gizmo layout  Possible perks  

 
 
 

Abilities  
Damage/Accuracy modifying 

Damage reduction 

Adrenaline 

Prayer 

Additional items 

Experience 

Skilling 

Miscellaneous 
