My little brother beat every level with 3 stars except for like level 5. He didn't use any Barracks or Reinforcements. So don't upgrade those. He just really went with what was coming. If big groups of like 20 monsters or something came, he put Bombards. Do not start off with just one or two Bombards. You need something fast like Archers. Bombards are good for groups of monsters. Mages are good for strong single targets. (Besides Shamans.) Archers are good for single target weak monsters. Once you get to like tier 3 and 4, Bombards are good for lines of people because of the explosion that when you shoot, like 7 little bombs come out, and if you get Tesla, it can do a chain lightning spell that hits multiple enemies at the same time. Mages are good for really strong monsters, (Likes Bosses) because of their teleport, and their burning effect. Archers are good for monsters with a lot of health, if they have the Musketeer upgrade. They can critical and headshot them, which takes out a lot of damage. If you upgrade them to Rangers Hideout, they can shoot super fast and poison the enemies. I'm not sure about Barracks, but if you need to slow down people, just get Reinforcements. Don't waste your money on Barracks. Upgrade Rain of Fire too. It can burn the monsters and it can rain in like 3-5 places in one click.
