The blood hunter is an unofficial Dungeons & Dragons Fifth Edition class created by Critical Role's Matt Mercer. Despite its unofficial nature, it's far more widespread and included than most homebrew, not least due to being available on D&D Beyond. Blood hunters pair martial combat with unique abilities that tap into blood's occult potential.
Source:https://www.cbr.com/dnd-5e-most-powerful-blood-hunter-critical-role-build/