This note should provide some guidance to those interested in gaining unlucky points. Those who aren't won't care much for this.
It is easily seen that 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 (each broken lockpick translates into an amount of unlucky points equal to 2.5 times the retention rate).
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 (which is good), but the chance of breaking the lockpick decreases (which is bad). 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 (in %) 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.
Note that there is not that big a difference when n (the retention rate) is close to 50. For example, 40 < n < 60 yields an average of over 60 points per chest. Nevertheless, when n differs substantially from 50, say n=14 for example, the average number of points per chest is reduced to about 30. This means that it will take a player twice as long to gain unlucky points when opening chests with this retention rate.
A player can't control the retention rate exactly but the above information may be considered when deciding where to farm unlucky points, and in which mode to do it (normal or hard).
L


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