he didn't use it on mifune....and had ms of shisui uchiha one of the best genjutsu user uchiha clan ever produce.....
He doesnt have ms, just bunch of threetomoed sharingans and already used kotoamatsukami that day so he cant use it against sasuke
He wan't to use it on Tobi apparently.
he wanted to use it on tobi...
He was going to save it up for Tobi.
He was saying it for obito