Evolution: Slow. Soulstones are in hero Ch.6 and Ch.8. You need to be relatively strong (4 star team) before you can farm soulstones in Ch.6.
Bloody is pretty useless early on, compared to other 3-star units she dies quickly, doesn't do a lot of damage, and her heals are not enough to keep the team alive. Things change once you unlock her fourth skill, however, and she gets enough gear and levels.Opinion by AzakaZero