Preparing a key block in a memory system. Various methods include: selecting a candidate key block of memory; checking a quality of the candidate key block using a word line of the candidate key block; altering operating parameters of the candidate key memory block; and registering the candidate key memory block as the key block. Where altering the operating parameters includes replacing a first set of parameters associated with the first memory block with a second set of parameters, where the first set of parameters includes a first erase parameter, a first program parameter, and a first read parameter, where the memory block operating in a normal block mode is accessed using the first set of parameters, and the second set of parameters includes a second erase parameter, a second program parameter, and a second read parameter, where the first memory block is accessed using the second set of parameters.