Well with the last boss fight operation considered a success they have released the second opponent! Same rules apply as before, so start sending those shotgun blasts, collecting the items from jobs, robbing, and fighting, and get some loot!
It seems the final mission combo is unlocked if you finished the prior mission sets from the last event! Just unlock the other 2 and your all set! And this time the harder the combo, the better the attack! (like it should have been from the start)