Warlock Pact: Pact of Blood
One of the most feared forms of magic, so-called "blood magic" is less of an entirely separate form of magic, and more of a unique method by which a warlock powers their spells. Other warlocks simply harness the power granted to them by their patron. Meanwhile, warlocks of a blood pact will instead then take the spells granted to them, and then power them—or even amplify them—using their own vital essence.
This method of spellcasting has benefits which are immediately, and sometimes violently apparent, but it is also especially draining, and exceptionally dangerous.
Pact of Blood Boon
At 3rd level, your otherworldly patron bestows a gift upon you for your loyal service. You gain one pact boon feature of your choice, which can be the following option.
Pact of Blood
When you begin to cast a warlock spell of 1st level or higher using your Pact Magic feature, you can choose to, as part of its casting, use your Pact of Blood to power the spell using your own life force. When you do, you don't spend a spell slot to cast the spell, instead spending a number of your Warlock hit dice equal to the spell slot level of your Pact Magic feature. For example, a 5th-level warlock's Pact Magic spell slots are of 3rd level, so they would spend 3 hit dice when they use this pact boon.
You must have a sufficient number of warlock hit dice remaining to spend in order to use the pact, and when you do, you also lose a number of hit points, as your own vitality is drained into the spell. The total number of hit points lost are equal to a roll of one of the spent warlock hit dice plus your warlock level. This hit point loss can't be reduced or negated in any way.
If the hit point loss from using the pact reduces you to 0 hit points, you don't fall unconscious until the end of the current turn or until you take damage, potentially allowing you to finish casting the spell. If this happens on your turn, you don't make your first death saving throw until the start of your next turn, though you still accumulate death save failures from taking further damage as normal.
Your Pact Boon
Like other Pact Boons, the Pact of Blood produces a special detail reflecting your patron's nature.
Pact of Blood. You are permanently marked by a brand, a scar, or even a tattoo which bears the likeness of a symbol or image relevant to your patron. This mark serves as the conduit through which you channel your life essence into your warlock spells. When you call upon your Pact of Blood, you can feel the mark siphon your very vitality into the spell. The sensation may be a freezing chill, a searing heat, or some other pain to be endured, depending on your patron.
Eldritch Invocations
Each of these invocations has a prerequisite for the Pact of Blood feature, meaning you must have chosen this pact to learn it. You can learn an invocation at the same time that you meet its prerequisites.
Blood Boil
Prerequisite: 5th level, Pact of Blood feature
When you cast a spell using your Pact of Blood feature, if that spell has additional effects for being cast at a higher level, you can choose to cast it at one level higher your warlock spell slots by expending two additional warlock hit dice, in addition to those spent to use your Pact of Blood feature.
When you do this, in addition to the hit point loss from using Pact of Blood, you also take necrotic damage equal to a roll of the two additional warlock hit dice spent.
Mystic Transfusion
Prerequisite: 5th level, Pact of Blood feature
Instead of casting a spell, you can use your Pact of Blood to infuse another creature with a portion of your vitality. As an action, you can spend hit dice as you normally would when using Pact of Blood, plus an additional number of warlock hit dice of your choice, up to half your warlock level. Roll these extra hit dice. A single creature you are touching regains a number of hit points equal to half of the rolled result.
When you do this, in addition to the hit point loss from using Pact of Blood, you also take necrotic damage equal to a roll of the additional warlock hit dice spent.
Empowering Blood
Prerequisite: 7th level, Pact of Blood feature
When you cast a spell using Pact of Blood, you can spend an additional warlock hit die in addition to the Pact's normal cost. When you do, you can roll that extra hit die and add it to the spell's damage total each time it deals damage to one or more creatures. This extra damage can't be inflicted on any one creature more than once per turn.
Prerequisite: Pact of Blood feature When you lose hit points from using your Pact of Blood, you gain a number of temporary hit points equal to the hit points lost. Additionally, any necrotic damage you take due to the Blood Boil, Mystic Transfusion, or Vengeful Blood invocations is halved.
Prerequisite: 12th level, Pact of Blood feature When you use your Pact of Blood to cast a spell, you can expend an additional warlock hit die. If you do, you can roll the additional hit die and add the result to any spell attack rolls you make as part of that casting of the spell. You then take an amount of necrotic damage equal to the rolled result of the additional hit die.
Resilient Blood
Vengeful Blood
Changelog:
v.1.0. First Draft.
v.1.1. Attempted to address notable balance issues:
- Increased hit dice expenditure to be equal to Pact Magic spell slot level
- Increased hit point loss from activating boon from simply equal to the spell level, to a roll of the hit die plus your warlock level.
- Blood Boil. Reduced upcast limit to a single level above your spell slot level, and clarified that the necrotic damage suffered is in addition to the base hit point loss from using the boon. Imposed 5th warlock level requirement.
- Mystic Transfusion. Changed name from "Blood Siphon." Decreased amount of hit points regained, and applied necrotic damage for using it, as with Blood Boil.
- Empowering Blood. Imposed 7th warlock level requirement.
- Reslient Blood. Changed negation of hit point loss to gain of temp HP.
- Vengeful Blood. Imposed 12th warlock level requirement. Removed save penalty option. Added necrotic damage.