The Crimson Lord (5e Subclass)
From D&D Wiki
Your patron is perhaps the first "Vampire", as some say. A nigh-primal being whose avatars thirst for blood. The blood coursing through the veins of all living things is a power few can learn to wield. The motivation of a "Crimson Lord" is unclear, but all those who serve one can attest to a bloodlust that lingers within.
Expanded Spell List
The Crimson Lord Patron lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.
|1st||ray of sickness, inflict wounds|
|2nd||warding bond, blur|
|4th||greater invisibility, death ward|
|5th||dominate person, geas|
Blood for Blood
At level 1, you may, as a bonus action, sacrifice HP to heal others. You may sacrifice HP (up to an amount equal to your Charisma modifier + half your warlock level (min. 2)), and restore a creature you can touch for an equal amount of lost HP. You must finish a short or long rest to use this feature again. This feature has no effects on undead or constructs.
Starting at 6th level, you know the spell Vampiric Touch, it doesn't count against the number of warlock spells that you know. When casting Vampiric Touch in this way, you add bonus damage equal to your Charisma modifier, and on a critical hit with the spell, you regain HP equal to the amount of damage dealt. If you already learned Vampiric Touch, you may pick another spell to learn at this level.
Drop for Drop
Beginning at 10th level, when you use your Blood for Blood feature, you may add your total warlock level, instead of half. When you reduce a creature to 0 HP, you regain use of Blood for Blood.
At 14th level, when you cast a damaging spell using a warlock spell slot, you can sacrifice your HP to deal extra necrotic damage with that spell for the first round it deals damage. For every 5 HP you sacrifice, you may deal an extra 1d10 necrotic damage, to a maximum sacrifice of 25 HP.
If you wish to deal this damage again the next round (such as if the spell requires concentration or a spell such as Armor of Agathys), you must sacrifice the same amount of health again at the start of your next turn, if you do not, exsanguination ceases to take effect.
credit to Gaming in Gotham. found on reddit. altered many things, but the base concept was not mine.