Currently my defense team is as follows:
Hu Tao 4/70
Kiril 4/70 (I plan to swap out Kiril for Boldtusk or Melendor as soon as I get one to 4/70.)
With what I have available, I don’t have a lot of room for improvement. The one thing I have considered is putting Cyprian in for Perfect Riposte. I’m just not sure I would gain anything, and don’t want to waste resources leveling him. His special is countered by 7 other heroes that are commonly used (Sonya, Caedmon, Tyrum, Melendor, Sabina, Belith, Zeline), so I’m leaning to sticking with what I’ve got.
I do have a few more 4*/5* heroes at max, but they are mostly offense-oriented (Marjana, Sonya, Tibertus, Wu Kong). Would any of them significantly boost my defense effectiveness if they replaced any of my current lineup?