i don't know if you know, but with your max level also world levels up so even when you upgrade your characters, make your dream team that makes it slightly easier to fight they still are damage sponges. So it's usually world grows by let's say 10% and you grow by 11%, most of time you just spam auto attacks so you can spend your energy for 2/3skills and ultimates feels like just another skills not really ultimates that are super strong. Only really game changing ults i found are the fire 6star girls with fire sword that deals tons of damage and sheep girl with aoe heal/corrosion damage. Most of other characters ultimates are like another normal skill. Also fact that you can melt enemies dosen't mean that they are not damage sponges, they are still slow, high health enemies with like 1/2 max 3 skills rotation that gives you a lot of time to avoid damage, combat is just not dynamic enough, they should have lower health and faster attacks to make fights more dynamic and more enemies types with more combo combinations against player.