That's just basic stratagy 101 friend. You Wait for the perfect moment to fire it. Tank LBs are instent because THEY are suppose to be taking the beating while Battle Dance and Heal Wave are charging to do their thing. As far as machanics go, you should NEVER fire Battle Dance or Star Shower during a One-Shot-Kill mechanic. You obey the mechanics 1st then pot shot the Boss AFTER his attack is over.