Help with Warlock Homebrew.

[MReav]

I am designing a Warlock homebrew called the Blood Pact Warlock. The fluff is that it's either a blood-eating nature spirit or a vestige of a once-powerful vampire trying to recreate itself. These spirits prefers bonding with tough, savage races, and sometimes even animals. However, they are wary of bonding with particularly tough creatures such as dragons, as they fear getting consumed by their would-be beneficiaries.

Pact Boon:

Blood Pact familiars are often Quasits that prefer remaining in vampire bat form.

Pact of the Blade:
A Blood Pact Warlock might use its own natural weaponry if they have them, or a morningstar with its spikes made to look like teeth.

Pact of the Tome:
Your Book of Shadows might be a leather bound tome written in blood, or written into your own body in scars.

I want the crunch to reflect that these creatures are casting primarily through their bodies, going so far as to use their Constitution for casting.

Unfortunately, I am kind of stuck on all the crunch related abilities. I have maybe its first level ability:

1st Level Warlock Ability: Blood Potency
For every Warlock level you have, add 1 to the number of hit points you gain. In addition, you can replace Charisma with Constitution for the purposes of Spell Save DC, Spell Attack Modifier, and Eldritch Invocations that involve adding Charisma to damage, such as Agonizing Blast or Lifedrinker.

I'm stuck on the 6th, 10th, and 14th level abilities, as well as the Expanded Spell List. The spells should be ones that cause bloody lacerations or make killing easier.
Spell List
1 - Bane
2 -
3 -
4 -
5 -

Any help would be appreciated.

[Ninjadeadbeard]

Easiest way to figure out what powers to grant the Blood Warlock is to determine what the powers are of his/her Master. Which oils down to how you view vampires. Are they deceptive-yet-debauched monsters who hide in high society? Are they shadow and twilight incarnate, leaping through windows and stalking prey silently in the night? Or are they Beasts, barely withholding their bloodlust in even the calmest moments, ready to rip entire rooms apart for their precious blood fix? Just pick a particular theme, and the rest should flow easily.

[MReav]

Easiest way to figure out what powers to grant the Blood Warlock is to determine what the powers are of his/her Master. Which oils down to how you view vampires. Are they deceptive-yet-debauched monsters who hide in high society? Are they shadow and twilight incarnate, leaping through windows and stalking prey silently in the night? Or are they Beasts, barely withholding their bloodlust in even the calmest moments, ready to rip entire rooms apart for their precious blood fix? Just pick a particular theme, and the rest should flow easily.

They're beasts. Not because I view vampires are such, but because the kinds of vampires that become Blood Pact patrons are the bestial remnants of destroyed vampires trying to pawn their power to some sucker that will give them blood. I saw an undead patron homebrew on Enworld, stuff like that can be the more sophisticated kind of vampire patron.

[Ninjadeadbeard]

They're beasts. Not because I view vampires are such, but because the kinds of vampires that become Blood Pact patrons are the bestial remnants of destroyed vampires trying to pawn their power to some sucker that will give them blood. I saw an undead patron homebrew on Enworld, stuff like that can be the more sophisticated kind of vampire patron.

Well alright then. Sounds like a Pact where the spirit isn't likely to have complex, non-rip-n-tear goals and desires. Likewise, I don't see subtle shadow magicks being a thing with them. Picking Blood Pact would seem to be the Warlock means to become a(n) (off)tank. Spells gained from the pact would all be either offensive Necromantic powers (Ray of Enfeeblement and such), or self buffs.

Off the top of my head, this Pact should give the Warlock the ability to drain health from his enemies. Something like the 1st level ability for Fiend Pact Warlocks.

[MReav]

I appreciate the advice. Just a point, while vampire vestiges are one type of patron, they're not the only kinds. I mentioned blood eating nature spirits, so if they would manifest as living beings, they'd choose vampire bats, leeches, lampreys, female mosquitoes etc.

[Amnoriath]

1. What you gave them here is being able to have a Fighter's health and stats with Warlock's. I am not saying this because I believe it is immediately breaking but it is something to keep in mind. In truth I think you should replace the 1 health a level with something else more flavorful to this. Since you are constitution focused this extra health is a little unnecessary, especially at this point. How about instead after a successful attack you force the enemy to make a constitution save or take bleed damage as well as being poisoned once until a short or long rest?

[Solzak]

How about something like the lvl 2 necromancer wizard affect (Grim Harvest)

Killing an enemy with a warlock power recovers 2hps per spell level, or 3 per level if it was a patron spell?