I don't recommended for leveling Carlini, because at a certain mission, he will died for defending Giacomo from enemy attack With his skill, he can blow up most enemy buildings with 1 Siege Blast skill

The third priority to level up is General Battaglion. If you can maximize her skill, she can summon more than 10 Gun Drones at the same time and also 2 Siege Zeppelin ! Because of her flying ability, cheap cost for summoning her and her ability to summon Gun Drones and Siege Zeppelin.

After all Giacomo skill has been level up, the second priority to level up is Venza. Imagine his Free Research Point and also his free Clockwork Men armies at every beginning of missions Prioritize to upgrade Giacomo skill first before upgrading other heroes, because at every mission, he always came from the beginning and it's FREE. Rise Of Nations - Rise Of Legends Tips and Walkthrough