Lockpick

Lockpicks were released with the addition of hard mode. In hard mode all chests are Locked Chests and require lockpicks instead of keys. Lockpicks have a base 10% chance of surviving the opening of a Locked Chest. This percentage increases based on the character's ranks in the Lucky and Treasure Hunter titles.

Using a lockpick to open a high-end chest adds 1 point toward the Treasure Hunter title. If you successfully retain a lockpick after use, you gain 250 points towards the Lucky title. If it breaks, you gain 2.5 points towards the Unlucky title for each percent chance to retain. For example: if your chance to retain is 73%, you gain 182 unlucky points since 73×2.5=182.

Lockpicks also work on all normal mode chests. If you try to open a normal mode chest with both the proper key and a lockpick in your inventory, the game will ask you which item is to be used. Each normal mode chest provides an inherent bonus to the probability of retaining the lockpick. The bonus is related to the value of the corresponding key so that chests with cheaper keys have a higher bonus. While opening cheapest chests with lockpicks doesn't provide valuable drops or points to Treasure Hunting, it is a relatively efficient method of advancing one's rank in the Lucky title.

Acquisition

 * Always available
 * Merchants for (or Discount Merchants for )
 * Pokhe in the Great Temple of Balthazar for 2 Silver Zaishen Coins and 50
 * From specific quests: Mano a Norn-o, Plan A, Shadows in the Night, and Single Ugly Grawl Seeks Same for Mindless Destruction in Ascalon
 * As a guaranteed drop from the Chest of Burrows after completing Frostmaw's Burrows.


 * Random drops
 * Opening a Royal Gift
 * Hidden Treasures in Dungeons (infrequently)
 * From Zaishen Chests (~2.3% chance)
 * From killing enemies (at about the same rate as key drops in the other campaigns)
 * In Hard mode, any foe
 * In Normal Mode, any foe in Eye of the North.

Lockpick survival chance for "Locked Chests"



 * In Hard Mode, the percent chance of a lockpick not breaking after use is:


 * 10 + (3 * Treasure Hunter ranks) + (2 * Lucky ranks)

Economic value of using a lockpick on Normal Mode chests
When a normal mode chest is opened with a lockpick, the total chance of retaining the lockpick is a combination of the base chance, as given in the table for Locked Chests, and an inherent bonus specific to the type of chest. This bonus is directly related to the value of the corresponding key, and given in the third column of the table below. The economic efficiency of using lockpicks in normal mode depends on the value of the respective key relative to the value of the lockpick, and the number of uses one gets from the lockpick. The second column of the table shows what the total retention chance must be in order for the use of lockpicks to be economically viable as a replacement for the use of keys. The fourth column indicates the base chance required to reach this break even point. Having a higher chance of retaining the lockpick than indicated in the table means you should use a lockpick. Having a lower chance means you should use a regular key. 1 This is the bonus given to your chance of retaining the lockpick when using on a particular tier of normal mode chests. 2 There is an approximately 10% decrease in this retention break even point if one is going for Lucky/Unlucky titles. See lockpick lucky contribution note below.
 * the percent of bonus needed from titles can be found by:
 * (1 - (Price of Key / Price of Lockpick)) = Inherent Survival Chance Bonus


 * Level 20 characters have a base chance of 10% even before titles are factored in, and thus using a lockpick is always a better deal than using a 1250 key.
 * If you purchase your lockpicks from a Discount Merchant, the base price of lockpicks goes down to 1200g per key, resulting in a substantial lowering of survival chance needed to break even. Discounted lockpicks will have a better value than discounted keys only if the regular priced lockpick had a better value than the regular priced key. Note that this does not mean you have an increased chance of keeping a lockpick, but that, since you can buy more lockpicks for the same amount, you can open more chests for the same amount of money.
 * See also Luck titles guide for a detailed cost/benefit analysis.
 * Note that using lockpicks also contributes to Lucky and Unlucky title, so there is an added incentive to using them over keys which give slightly better value per use. The monetary value of this Lucky/Unlucky title contribution has not been factored into the above table. The value of a lockpick with lucky+unlucky points obtained from it added in is approximately 305.6 worth of playing 9 Rings.
 * If one is going for both lucky and unlucky titles in addition to wanting to know the least expensive way of opening treasure chests (and gaining Treasure Hunter points), the use of a lockpick would be advisable (take into account the above table, find the appropriate break even point and take into account an additional 300). For example, with a 26% retention rate it would be beneficial to use lockpicks for 600 and 450 key chests as well. Thinking of it another way, the lucky+unlucky feature of lockpicks reduces the retention % break even point by 8-11% (10% for most of the chest key categories), so you would need a 15% (25-10%) native retention rate or higher in order for a lockpick to be more beneficial than a key for a 750  key.

Theoretical calculations for maxing titles
This table shows the theoretical number of lockpicks needed to gain levels in the Treasure Hunter and Lucky/Unlucky title tracks, assuming you are starting from 0 in all titles and all lockpicks are used on high-end chests in normal mode, i.e. having a base retention rate of 40% (30% for the chest + 10% for being level 20). Each row shows the cumulative totals at the point that a level is gained in either the Treasure Hunter or Lucky title, the bold number indicating which title increased. (Unlucky is not noted similarly, as it does not affect the retention rate.)

Since this is a theoretical analysis of title progression, the table does not take into account such things as income from selling the items you get out of chests or buying lockpicks at a discounted price.

The Unlucky title will be maxed first, then Treasure Hunter, and finally Lucky. If all Lockpicks are purchased from merchants for 1.5 each, the cost to max Treasure Hunter is approximately 5638, and the cost to max Lucky is approximately 7942.

The Optimal Retention Rate for Unlucky Points
If one would like to gain unlucky points while breaking a minimal amount of lockpicks, then opening chests with a high retention rate is the way to go about it.

But what if one doesn't care about the amount of lockpicks broken and instead only cares about gaining unlucky points as fast as possible, that is, opening a minimal amount of chests.

As the retention rate increases, the (average) amount of unlucky points per chest increases, but the chance of breaking the lockpick decreases. It turns out that opening chests with a 50% retention rate will maximize the (average) amount of unlucky points per chest.

The calculation can be performed as follows: denote the retention rate by n. The average amount of unlucky points per chest is the chance to break the lockpick 1-n/100 times the unlucky points gained (2.5n). This is 2.5n - n^2/40 which is maximized at n=50, yielding 62.5 unlucky points per chest.