Numeric, and otherwise, wordlists have patterns that are unlikely to be utilized by software which creates the key based on 'random' digits. Repetition is an obvious one, but all patterns must go.
febf2cff (utilizing the 'f' 4/8 makes this key highly improbable to be generated randomly)
Obviously, this can drastically reduce a wordlist's size; a necessity if you want to challenge larger keys.
It seems this has been covered elsewhere but I cannot find a reference: Does anyone know of an existing program that does such a thing, or am I delusional? I realize there are numerous rudimentary ways to do this, but its seems as if there is already a program specifically for this. If not, its off to the coding board!