For the last bonus mission same gear and stuff kill the dual wielders first then priests uses the ultimate a boss comes every 2nd round so 2 4 6 they go from the pit to colesium so mikus wizard guy then Pontius try to save a uptime for Pontius which will start with the large Area attack spell you could still kill him without the ultimate easily.
I will tell how to do the 2 first bonus missions. For the first get black boots and for the rest of the gear get the second best such as the white helmet and armor for the cape get the white cape. FOR WEAPONS make sure to get the black shield. The goal of this idea is most damage per min with the ultimate you should get a ultimate at least 10 sec after you just used yours. For the abilities get quake and as much large potions. For the sec bonus mission same gear same stuff kill the blue guy first then the gold guy you should have or almost get the uptime there after you killed those two if not try to take lil dmg and attack as much as can when he heals.
The reason why you do less dmg than it says like 80 but it does 30 is cause they have ARMOR aka DEFENCE which lowers the damage just like yours. If it takes too long I suggest you use the duel wield type of weapons they hit quick and do lots of dmg takes even brutal behemoths 8 sec with the said.
I would go as far as to say for lvl 9 with the first story you should let verc get the wizard cause he dies easily with the spam I stated as well as there won't be any boar riders or behemoths to block the dmg done to the base. I did test it.
I straight up for the last lvl for Caesar's campaign used lvl 2 fire archer range plus lvl 3 speed for miners and would of won the game without help from Rome. Lvl 9 for the same campaign was easy too you have 5k gold you get 3 centurions highest Def cavalry and max range fire archers spam that it is the easiest stuff. Pro tiP fire archers are the best unit for Rome.
Its so good, that I straight up almost maxed out all my soldiers after that I will try to get the max $$ I could get for each soldiers which is 999,999?