Blood hunters are clever warriors driven by an unending determination to destroy evils old and new. Armed with rites of secretive blood magic and a willingness to sacrifice their own vitality and humanity for their cause, they protect the realms from the shadows — even as they remain ever vigilant against being drawn to the darkness that consumes the monsters they hunt.

Source: DND Beyond

You must have an Intelligence score of 13 or higher and a Strength or Dexterity score of 13 or higher in order to multiclass in or out of this class.

If your blood hunter is part of the Order of the Profane Soul and also has warlock levels, add one-third of your blood hunter levels (rounded down) to your warlock level and consult the warlock progression table for total spell slots, cantrips known, and spell slot level. You should consider aligning your Otherworldly Patron feature between both classes, but your DM might allow you to have two different patrons at their discretion.

Variant Hemocraft Ability Score:
As a blood hunter, you use your Intelligence modifier for some of your class and subclass features. However, with your DM’s permission, you can choose to instead use your Wisdom modifier for all your blood hunter features that use your Intelligence modifier by default.