The way the camera moves with your cursor makes this very difficult to play. I love the game, but you may want to look into making it so the player is centered at all times.
I beat trial one using hell raiders, paladins, taurus oxen, wizards, witches and succubi, and equipped the rangers for damage and melee for health, and used rage to up the attack of rangers, so try that.
The hero became a liability in this game. I liked the old style better where each side had a base. This version introduced interesting new ideas, but they need to be refined.
It would be better if you could control when you shoot. Your gun is unpredictable so it made it difficult. Difficulty should be added by complex enemies or something that involves skill, not by an unreliable gun.