Thought I’d do the math and try to summarize the effects of combining troops and class bonuses. The brief summary is as someone said earlier, if you have maxed mana troops class bonuses generally don’t make a difference. However, class bonuses do lower the troop level required to hit certain tile # thresholds. Example being a Ranger/Rogue like Athena/Domitia with average mana speed. Instead of requiring level 23 mana troops to require 9 tiles to charge, they only require their class level 8 mana bonus plus level 17 mana troops.
So much of this is situational, but if you get a class bonus it could definitely lower the troop level you need to drop the number of tiles needed to charge a special.
The dumb part is most of the mana bonuses don’t come until level 19/20. So maybe in a year this will become useful? 