@Jronny There are some really good tank options outside of Telluria. The obvious choice if you have her is Ursena. She is a beast! Beefy, average mana and punishing. Outside of Ursena, there is the obvious selections, Guinevere, Kunchen, Heimdall, etc. An early posted showed what the top tanks were before Telluria came out
October 2020 Balance Update - Discussion
Feb 2020
I think we will see these tanks in uses the most at least until other options like Frigg come out.
In your case, Costume Kadilen is a definite options. Her stats are solid especially if you play with the emblem options. Here is a sample one I found a couple of months ago.
With the decrease cost to emblem a hero, you could easily get her ready to go ASAP.
Based upon your roster, your suggested lineup would work great for your main defense. If your alliance uses Green tanks, it will work for your war defense as well. If not, you have options,
Blue - Ariel, Aegir
Red - Grazul, Mitsuko
Purple - Clarissa, Kunchen, Alfrike
Yellow - Guinevere, Drake