So at level 3 Fatesinger while taking the '+1 extra song' passives up to 'Reign' I have 11 songs of 'Reign'. I got a total of 33 mins of 11d20 sonic + lightning on confirmed vorpals
NOTE: Currently you cant regain the charges via shrining or tavern up-keep. You have to re-twist 'Reign'. Not sure if this is WAI, imo this is a massive bug so I sent in a ticket(knowing Turbine it wont get 'fixed' for months).