In order to beat enemies in kingdom rush game, you must build all kinds of towers to defend against monsters, from an archer tower to a mage tower to an artillery tower, and even upgrade them, as well as earning diamonds and stars along the way.
Build alternate barracks towers and artillery towers.
The militia in the barracks towers will force enemy forces to stop and be held up your kingdom
The artillery towers will bombard and do area damage to the range of enemies that are getting held up your kingdom.
Use the reinforcements in a similar location to your militia rally point to do even more damage.
Just start changing the plan to alternate mage towers, barracks towers and artillery towers, so that the mage towers can pierce through enemy armor, allowing barracks and artillery to move away armored opponents much more quickly.
Always make sure to stock up in the shop for some extra weapons to defeat Large enemies such as ogres.
Stock up with dynamite that is cheap and effective, as is the Frozetov, but any of the weapons will work against tough enemies like that.
Use the gold to rack up and to upgrade your artillery and magic towers in order to do large amounts of damage.
Always play every level in both the easy and normal modes to rack up stars and to get stars for both types of levels.
Do not even bother upgrading your barracks if the only point of having them is to slow enemies down so that they can be shot more easily by the other towers.