I use 3 stars and 4 stars as the filler for 5 star in low level. Some 3 stars are really good (as strong as pre gifted 5 star ) are Marigold, Astral Galus (special skill) and Rose diana (high attack state). A team of 3* and 4* combine can kill maximum 2 mob in 80 stamina map and a few 5 stars are still necessary to prop up the whole team. 3 stars are valuable resource if you want to save up gems when you first star playing game. , this is my team in total power order (i upgrade 3 star in dmm ver cause there are a lot of manyus reward ).