Final Bankai should be able to be used for 350 seconds and should be master-able by hitting with it on and using Mugetsu (Kind of like Vaizard Mask). It should take a long time to be able to master it and Mugetsu should have a cool down of 35 or more seconds. When using Mugetsu, it shouldn't drain on the time limit as it gets mastered. For example, 10 Mugetsu's add on 10 more seconds of Final Bankai usage until capped at 350 and once at 350, Mugetsu takes 9000 rei or so. Mugetsu shouldn't drain all Rei, as it is mastered, it should take less Rei to use.
