Possible to get 5-star and i used 400 gems summon cus it saves 50 gems that way. I got a 5-star valiant from that and 2 other 4-stars. There's not much to summoning. Either you summon now cus the pool is still small and higher rate of 5-star or you wait for new chara or promotions that increase your rate of summoning whatever chara u like