tbh I have no idea but you'll just have to wing it somehow if you want to try 3* it. I myself used 17 cost(mincost) claudia to replace 1st bandit, and dropped (15 cost, CR1) elaine to take out 2nd black gob archer (healers were iris at 19 cost cr1, and alissa 17 cost cr1). I then withdrew elaine, placed rika at where she was supposed to be and placed charlotte to handle the next wave + lich. so basically my strategy will be hard to replicate for you.