u lvl up a ls charecter to 71 then there will be a option of master questing
when u do mq first feeder classes and sammy and pally i think will have 3 keys u must put in order in order to pass to next unlockable class
say if ur a barb u mq'd
u got a silver / bronze / gold key
and 3 doors
u must put those 3 keys in order
ex. it can be bronze / gold / silver
or bronze / silver / gold
or silver bronze gold
or silver gold bronze etc..