I would like to propose to the developers in order to unlock the different Torment Difficulties, you have to not only complete the required pit levels but also clear Pinnacle Bosses guarding the various Gates. There would be 4 Gates in the Pit that corresponds with the 4 Torment Difficulties. These Gate maps would have a different layout and you would immediately enter a throne room to fight a Pinnacle Boss. The first Pinnacle Boss would be Cerberus, which seems fitting guarding the gate to Hell. The second would be a Coven Witch and the last two would be Azmodan Lieutenants.
Unlock Torment 1
- Complete Pit Levels 1-20
- Clear Pinnacle Boss at Gate 1
- Pinnacle Boss: Cerberus (three-headed dog)
Unlock Torment 2
- Complete Pit Levels 21-35
- Clear Pinnacle Boss at Gate 2
- Pinnacle Boss: Coven Witch Maghda (minion of Belial)
Unlock Torment 3
- Complete Pit Levels 36-50
- Clear Pinnacle Boss at Gate 3
- Pinnacle Boss: Cydaea (Maiden of Lust)
Unlock Torment 4
- Complete Pit Levels 51-65
- Clear Pinnacle Boss at Gate 4
- Pinnacle Boss: Ghom (Lord of Gluttony)