I got my idea inspired by Diablo Horadric cube :) that we will have one additional gateway that will combine 12 type of mats to open an instance for player. This instance will just open for the one that deposit mats , and he is able to invite up 3 players to join his party. However, they have to be remain in party ( not allow other invited member to go solo and then invite others ). For example , to use this gate , I have to go down to depth 0 (instance) and I will deposit 12 random type of material in the machine nearby, and it will generate one stratum (theme is decided by materials ) that have 7 depths (there is a list showing gate's theme ). Player may wish to deposit other mats again so the gate will generate other new stratum. If players happen to have right formula , they may discover one of many secret stratums :D !