Something else you should consider is checking the scales and the 2nd row of creatures incoming. If there is a wriggling tail, or wriggling feathers that is blocking a stronger creature, keep it in the back row. Not sure if you noticed that you should compare the damage you do in a turn to what you will receive from your opponent.

Hello Dan. Today for nostalgic purposes, I decided to use a random starter deck and go for the skull rush achievement in Kaycee's Mod. That's 250 challenge level. I only needed to restart battles 5-8 times and win the run. You may wonder why that is. Well, why do you think there is an option on the main menu screen called "Continue Run"? Anytime you feel you will lose a battle, you can quickly get to the main menu and click on continue run. This allows you to restart battles instead of having to start from the beginning. It's a timesaver if you are serious about going to all 12 challenge levels of this game.