Most important thing is first deciding who will be your tank. Drake, C.Kadilen and Richard could be candidates.
Blue: Richard, Skadi, Magni, Alice,
Green: Alby, Zeline, C.Kadilen, Kingston, C.Lianna
Purple: Hel, Sartana
You only have Marjana for red and Drake for yellow so those 2 are going on the defense. Between Hel and Sartana, Sartana is preferable for defense team imo. Hel does well offensively but for a flank or wing on defense, I’d rather go with Sartana.
That leaves blue and green. For blue, I would only use Richard as a tank. Skadi’s monk class overlaps with Drake so she’s out. Magni and Alice are both good flank/wings but Alice’s rogue class overlaps with Marjana. That leaves Magni.
For green, Kingston’s fighter class overlaps with Magni. Alby, Zeline, Lianna+CB and C.Kadilen are all viable choices for defense.
If you want a green tank: Sartana - Drake - C.Kadlien - Magni - Marjana
If you want a yellow tank: Sartana - Lianna+CB - Drake - Magni - Marjana (or other order as long as Drake is center tank)
Alternatively, you can switch out Lianna+CB for Alby in left wing: Alby - Magni - Drake - Sartana - Marjana
My personal preference would be the first choice with C.Kadilen tank.
Another option would be to ignore the class emblem conflicts. E.g use both Marjana and Alice but have one (or both) unemblemed until you get a new red hero that is good for defense (and then switch out Marjana). Same thing with Kingston who is also a good defense hero.
You have a lot of options with different combinations. Try out a few and see which one works the best for you.