how can i make an ability take a while to cast and lower defense, it is for the first form of the last boss Options

[andreasaspenberg]

i want the last boss to have 2 forms. the first can only be harmed when it charge its ultimate attack and the second can only be harmed by ultima and the ultima weapons.(the first form can also be harmed by ultima but it consumes all mana so players should save up the mana for the second form.)