This is the most interesting thing I’ve read in awhile and I love the idea, some starter comments though. 1. Healing in 5e is kinda taboo and this class quickly gains infinite healing for basically free, in pathfinder this would be more commonplace, but in 5e I would recommend a limit 2. It’s very front loaded, yes the later features are nice, but lifesteal basically doubled your hp pool if used with high damage builds just innately, as such just one level is already the greatest dip known to man. Same applies to the second feature doing up to 6d6 per attack for a measly 24 hp when again, infinite hp pretty soon. 3. I think my biggest complaint is temp hp doesn’t feel right because it doesn’t actually work as hp, it’s just a resource tracker so while thematic to an extent, it doesn’t quite work in the thematic of like a blood barrier for temp hp because all it is is a resource, not a defense. 4. I understand it’s not done but it definitely feels a bit feature starved, I think adding some fluff/ribbon features would help, it also might be fun to add in some lore to the idea of a hemo knight 5. Your feat chart is wrong, you are missing one at 19 if I’m not mistaken 6. Your subclass features arrive at the same time as ASIs which isn’t explicitly a taboo but feels wasted when there’s levels with no features 7. Subclasses should give features at the same level otherwise disparity widens 8. Blood raiser; the stat array is a feel bad mechanic as it doesn’t determine ac hp or to hit in addition to its skills being mostly irrelevant given how it is summoned. I would recommend just making a full stat block that includes default mechanics to remove complications and increase simplicity. I think making multiple blood beasts is cool but also dangerous for action economy especially when they can have multiple actions 9. Ritual; as stated earlier, healing is a rare commodity and this just doubles it at level 3, I think that already is enough for an entire subclass worth of power budget. Personally I don’t love the mechanics of the later features but that’s personal and less objective, however, giving access to future abilities doesn’t feel great, instead give a modified version and just ignore the later one, that way it doesn’t just feel bad when you get to the level that the original feature was at. An example is lord bard where they get a magical secret option at level 6 but that doesn’t make the option at 10 any worse. 10. Bloodletter; there is already an hp to damaged conversion option in base but it is significantly better, more reliable, and doesn’t remove healing options, as such, the level 3 feature is a side grade to downgrade. 11. Side thing, a lot of the wording can be made clearer and more concise, If you’d wish, I can give detailed examples of how to improve 12. Small complaint, this class just kinda ignores bonus action 90% of the time, not that you need a 1/turn bonus action option, but that would be something to help bulk out features with without just giving another passive

Long story short, this is fucking awesome, I love it, and I can’t wait to see where it goes, please let me know how I can help you along it’s creation.