Assuming you’re on a server with a 70 level cap, if your whole team is 4-5* and fully maxed out, it’s all about the timing of when you activate skills (you should be playing manual, if you already aren’t).

If you are not on a server that has level 70, or your team is under 4*, not completely maxed, you should do a different campaign until it is, and then try again!

This applies to most high level campaigns btw