I’d agree with the @Radar1 setup with what you list, although I’d prefer a rainbow defense to keep any color from being especially vulnerable. Mel is better as a healer than Cyp, and BT is better as a tank, but as you I’d be looking for a good purple (Tibs?) to sub for Jack.
Healers are always helpful on defense, and Mel + BT are two great ones. Sonia is good as a debuffer though I had and preferred Caedmon. I had Chao in for a long while as a defender; he worked fine. GL!