The removal of lava burst is not so much the problem as it is what they put in its place. 5% crit to lightning spells is the most bland thing I could think of for a capstone. It’s almost like they just don’t give a crap. Enjoy your one button since you are going to complain, basically.
Once you actually work out the rotation and Mana costs there isn’t a whole lot of room to use any chain lightnings in a 3-minute fight.