3. Spirit Mage
4. Thunder God
5. Pirate Captain
Engineer does a great job at replacing the SM in the closest way in terms of mechanics. Ranged AoE. Not near what the SM is capable of but close from a mechanical standpoint. Other great options are the Ninja and Champion. Succubus is nice because she has a lofty HP but her ability is seriously terrible in raids.
Trust me, I LOVE my Champion, but he doesn't fit this team as well as the Paladin. While he is tanking 4 camps, 5 towers, and 5 heroes the others are dealing that AoE DMG and demolishing the entire base around them.