How does this homebrew Warlock "Patron of the Old Blood" compare with official patrons?

Question

As I've developed further into DMing and the path of creation that follows, I've started to understand a need for more subclasses. And I've continuously toyed with the idea of a more occult style of warlock. With that said, I took many sources of inspiration to create this Old Blood patron. And after quite some time, I am at least confident in the concept and skeleton of what I've created. However, this marks my first foray into subclass creation. So with that said: Does this homebrew patron retain balance compared to official DnD 5e Patrons?

The Old Blood

You have signed a sanguine pact with a member of the Crimson Court. A powerful vampire lord or a nameless god of blood rites now uses your blood as a conduit for power. Are you a pawn in a millennia long design to spread a blood curse across the material plane or do you act as a blood conduit, constantly being siphoned of your life force for your power?

Perhaps you sold your services in exchange for a chance to escape dark powers. Or you delved into forbidden blood magic rituals to gain power. Now, you constantly leak small amounts of blood that strangely seeps back into your body. Even other creatures' blood that's nearby will work to find a way inside your skin.

Expanded Spell List

The Old Blood 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.

Old Blood Expanded Spells

Spell Level	Spells
1st	false life, inflict wounds
2nd	blindness/deafness, gentle repose
3rd	bestow curse, revivify
4th	compulsion, confusion
5th	dominate person, mislead

Hemorrhagic Shock

At 1st level, you gain the ability to stave off death from exsanguination. You stabilize automatically whenever you are dying at the start of your turn.

In addition, you learn the spare the dying cantrip, which doesn’t count against the number of warlock cantrips you know.

Blood Boil

At 1st level, your cursed blood can be so volatile that it can cause damage to those who do you harm. As a reaction to being hit, you can cause your blood to boil in air, dealing your charisma modifier + your warlock level in necrotic damage to creatures within 5 feet of you.

You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Crimson Tithe

Starting at 6th level, you can tax any wounded creature of their life force. As an action, if a creature within 60 feet of you is below its hit point maximum you can force it to make a Constitution saving throw against your warlock spell save DC. On a failure, they take 6d8 necrotic damage or half as much on a success. You gain temporary hit points equal to the damage done.

Once used this feature cannot be used again until you finish a short or long rest. This feature has no effect on Constructs or Undead.

Sanguine Endurance

Starting at 10th level, your control over the old blood grants you increased heartiness and the ability to maintain focus even when taking severe wounds. You gain proficiency in Constitution saving throws and your hit point maximum increases by a number equal to your warlock level.

Scarlet Dominion

Starting at 14th level, you gain the ability to soak the lands in blood, creating a temporary domain for those who feed off others. As an action, you create a 120-foot-radius circle of blood-soaked land centered on yourself. When you use this feature, you can designate any number of creatures you can see to be unaffected by it. When an affected creature enters the area for the first time on a turn or starts its turn there it takes necrotic damage equal to 2d8 + your Charisma modifier. Additionally, on subsequent turns while you are inside the area you can use a bonus action to do one of the following:

• Give a creature temporary hit points equal to 2d8 + your Charisma modifier.
• Force a creature to make a Constitution saving throw against your spell save DC. On a failure, the creature becomes stunned until the beginning of your next turn.
• teleport to an unoccupied square within your circle.

This area lasts for up to 10 minutes or until you are incapacitated. Once you use this feature you cannot use it again until you complete a long rest.

Answer 1

First, I want to say that I like the idea and effort put into making original and thematic abilities for this subclass. But, I think, there may be some balance issues.

Expanded Spell List - nice spells.

Hemmorhagic Shock - nice utility ability to have. You forgo a chance to stand up on rolling 20 on stabilization to guarantee that you won't die. Teammates would still have to spend resources to heal you back into combat. On the other hand - due to this ability they may not worry about hitting your unconscious body with AoE spells. I'd give it 3.5/5 power-wise, since it's a very useful ability, but limited only to certain situations - and healing of those, who are dying is relatively easy in DnD 5e.

Blood Boil - damage is relatively low to be meaningful past starting levels, but against many low-hp enemies may be nice. Recharging at long rest means that it's impossible to spam this ability. 3/5 power-wise - because ability has a nice damaging potential (even on level 1, if there are 8 enemies around warlock, it can deal 32 ((1lvl+3CHA)*8) damage) and it's not dice-based, but it requires to be extremly lucky with positioning and such position (in the middle of enemy group) tends to be quite risky. Also, it damages nearby friendly characters.

Also, most warlocks get only one ability in adition to Expanded Spell List at first level. Exceptions are only Hexblade, Celestial and Fathomless

Crimson Tithe - that's a very good ability, maybe too good. At 6th level, when you get it - it can almost double warlock's hp ( and being recharged at any rest, means that it can be spammed quite often. I can think of several schemes to abuse it. (For example - take one of 'elf' races that, according to MPMM can finish long-rest in 4 hours, buy/capture a number or rats or other small critters. Upong finishing long rest squeeze one of rats, opting for knocking it out non-lethally. Use Crimson Tithe. Do short rest. Start the day rested, with temporary hit points and a charge of Crimson Tithe ready again) 4.5/5 power-wise. Celestial at 10th level grants more temporary HPs (54-60 at 10th, gettign to 90 at 20th) - but they are spread over warlock and 5 companions.

Sanguine Endurance - that one is also good. While warlock doesn't rely heavily of concentration-based spells that require constitution saves, they are still among three most often encountered in game (along with Dexterity and Wisdom ones). Extra hp is also good. 4/5 - power-wise. At level 10 warlock has 17-80 hp (not counting CON mod) if you roll for hp and 53 hp if using fixed values (not counting CON mod), so 10 hp is about 10-20% increase of HP pool.

Scarlet Dominion - that's ability that is too good. It's DoT with huge AoE that doesn't hit friendlies and allows warlock to evade hostiles, control them and buff friendlies. You don't even have to concentrate to maintain it, it just exists. Downside is that damage is not that great, but it doesn't allow any saves and can soften enemies - still it's an only reason to not call ability OP, but it's still - 5/5 power-wise, as it's hard to compare to anything what other warlock subclasses have.

Result - powerful subclass focused on combat. 5/5 in combat-oriented campaign. Many abilities give spikes of power at the level when they are granted that go down with further levels.

I'd suggest to consider flattening those spikes, by making abilities more level-dependent

Answer 2

The subclass reasonably uses balancing tools

Negative effects allow saving throws (except Scarlet Dominion), the different abilities are tied to the action economy where useful, and use limits are in place where useful.

The subclass is rather strong compared to other subclasses

I compared your subclass's features to those of the Great Old One, the Archfey, the Fiend, and the Hexblade. On all levels, your subclass's features tend towards the strong end of the spectrum.

Spell List

There is something wrong with the level column. The choices seem mostly unproblematic, although Inflict Wounds is one of the highest damage spells at the level which may be a bit much, especially with the other abilities given at level 1.

Level 1

Blood Boil is strong compared to other level one Patron features, mostly because it has multiple daily uses and potentially multiple targets per use. Hemorrhagic Shock seems unproblematic for balance purposes but given that Blood Boil is strong already as is Inflict Wounds there seems to be too much benefit on level 1. Notably, this isn't counterbalanced by weaker benefits on higher levels.

Level 6

Like the other subclasses, yours has a once per rest ability at this level. The damage seems balanced given that the use costs an Action. The expected damage is 27 against 19 for Eldritch Blast (assuming Agonizing Blast and CHA+4). However, the amount of temporary hitpoints provided is pretty large, making this feature comparable or superior to the features of the other subclasses.

Level 10

Like the other subclasses, yours gets a defensive bonus at this level. Your bonus is significant and very broadly useful, more so than those of the other subclasses, making this feature again tend on the strong end.

Level 14

At level 14 the other subclasses get impactful features, however those are restricted to a single target. Yours however has to be assumed to affect almost every opponent for the whole combat duration in most combats: 120 feet is a rather large area, ten minutes is longer than most combats, and knocking out the user is the only way to evade the effects of the feature. This means your feature will tend to deal significant damage (the amount per time dealt is not very big, but it will generally affect every opponent every turn and even without saving throw). Even outside this, the feature is benefit packed with the damage and a variety of useful effects to choose from every turn. Importantly, a stun effect is very strong as well, even if for only one turn and with a saving throw, because it will generally take an opponent completely out of the combat and make it much easier to damage them. With the huge area, strong stunning effect, (almost) impossibility of ending the effect, and the missing saving throw for the damage, this is the most important feature to modify.

Conclusion

The functioning of the features is in line with published class and subclass features. The power level of the subclass is high overall. The level 14 feature in particular is overpowered. The level 1 features are reasonable individually but probably too much combined. The temporary hitpoints of the level 6 features are maybe problematic.