For fast sparkly corals, continue running the event and get raid bosses. Either participate in these or if a higher level boss is available attack that. Since the participation reward is static depending on the raid boss level, it wouldn't matter how much damage you dealt. Continue pumping out bosses even if you don't participate in them as you do get a discovery reward as the provider of the boss. Do note that you should be careful pumping out bosses as you don't want to end up in a situation where you have full raid points with no stamina.