Should I use a generic gem on 4* medusa

taojay1

Just won her from arena. I know she kinda needs the dupe to be good. I have 6* bb and 5* karnak, and 2 basic gems. I currently lack dv, aa, wolvie, gr, blade tho, and I have many decent 5* cosmics (4/55 drax, plus 2/35 angela, marvel, phoenix). Is medusa worth r5 and one of my gems? I really don't use 4 stars much anyways and won't be r5 many more in the future, but I do like medusa.