https://youtube.com/watch?v=IkC1r0eJZ-c&t=313s
Malefic IV cast straight in front of you.
Then what follows is your new instant spell, obviously a shield. It most likely boosts stats as well, seems like a 1-2-1-2 rotation. You see the AST casting another
malefic cast(behind the bard) which is followed by the same
new spell.
It is possible that the new spell is actually an oGCD with a short cd or it can stack like Essential Dignity. In any case, it is going to be something you play around. If it is GCD, it is going to be more than a shield, if it is oGCD, it probably becomes available after Malefic casts.
Also, since AST is casting Malefic IV, you can speculate that healers did not get nuke upgrade at level cap. At least AST didn't. Healers will need an increase in potency which they could get from somewhere else.