I enjoy the thematics of this class option, but it really lacks a lot of the things I look for in a 3rd party supplement. I have a decent number of issues with the way things are laid out and what we can (and can't) do with this class. I'll list out the good and the bad, and offer some possible solutions I've come up with in the couple days since I've had this PDF.
The domain spells are pretty cool honestly, most of them exemplify the idea of being a bursty, damage dealing cleric. Certain spells, like mirror image and magic circle (along with the wall spells), don't really seem to fit too well, but they're good utility spells just in general to have on any spellcaster.
Again, not too much to complain about, if you're going to make a frontline damage dealing cleric, it's good to have the proficiency to use the highest damage dealing weapons, and the armor with the highest AC. It would probably be nice to have some flavor proficiencies, such as Athletics to signify your physical tempering needed to be a martyr, or Survival to signify the hardships you might have put yourself through during your study and dedication to a god that values putting your body on the line for others.
Here's where I have my first major complaint with the class. The main issue with how this is written is that there's no bounded limit to the amount of added damage or healing someone can add using this feature. With the Rules As Written approach, a player can add an unlimited number of hit points to any number of attacks they currently have. If someone figures out that the goblins each have 10 HP, and they roll a 6 for damage, they know exactly how much HP they need to dump in order to finish the goblin off, and the encounter just boils down to "How much damage do I need to take to finish off this creature?". My suggestion would be to have this feature be the first time we use Hit Dice as a currency: Once per turn, you roll a limited number of Hit Die (perhaps up to half your cleric level), taking that much damage, and you can add either healing or damage equal to the amount of damage you took from the roll. It still gives the feeling of risk from sacrificing your own vitality for extra effect, but prevents the intense calculations of dumping the exact number of hit points to kill a creature if the player knows what the damage threshold is.
Channel Divinity: Sacrifice Self
This one is probably the most egregious error of the Domain as a whole. I think there's a good base to the feature, and it is extremely thematic to the idea of martydom, but the execution is lacking severly. There's so much that is unmanageable about this feature. Every creature within 30 feet takes the damage, so you have to already be in a good position to avoid catching allies and (more importantly) as many enemies as possible in the blast. Which means you can't press the self destruct button too late in the fight, or your friends are likely not going to make it out of range safely, or you only catch some enemies, but not ensuring the rest of the party's safety. Then, the damage is ok for dealing with most threats, but if you're dealing with a boss monster, you have to ensure that you've dealt a decent amount of damage to make the sacrifice worth it, otherwise you've just contributed to the death spiral, and you (as the cleric) have left the rest of the party with much less support than if you were alive. And finally, the kills the character instantly tag really limits the use of this feature. Of course you want this to be a "final gambit" move, but there honestly may not be a good opportunity to use this ability, or I might have grown heavily attached to the character, and it really locks the player out of, essentially, the key feature of this class. Changing just a few key words would really make this a useable feature and make it useful and impactful throughout the campign, but still have that intense all or nothing risk factor we so love. First, I would rework the damage, allowing the player to Expend a number of Hit Dice, then roll a number of d12s equal to twice the number of Hit Dice you expended. You and each creature of your choice within 30 feet of you takes that much Force damage. Any creature brought to 0 HP by this ability is instantly killed, and cannot be brought back to life by anything short of a Wish spell or divine intervention. This allows the player to risk big to deal a huge amount of damage to a number of creatures, avoid any friendly fire, and it doesn't (immediately) end a character's career, but still has the chance to if the player makes a bad gamble.
Last Man Standing
Another really good start to a feature, but lacks the final touch to bring home the reward part of the "risk reward" factor. I like the idea of making a final swipe or two at an enemy before you go unconscious, and there's already a limit of once per long rest, so there's no need for extra bounds to prevent abuse. I would add in a small adjustment to the text to give the player a nice bonus: When an enemy reduces you to 0 hit points, you can use a reaction to make UP TO two melee attacks before falling unconscious. Each successful hit gives you one death saving throw success, and each miss gives you one death saving throw failure. I believe this would allow a player to, again, make the choice to risk big for extra damage, and possibly an easier time getting back to stability, but also the chance to really whiff it and cause serious tension over the next few rounds.
Similar issue to the Tunnel Vision feature, no hard limit on how many times you can use this feature (aside from the obvious Hit Dice limit), but also it doesn't feel wholey unique with the myriad of raw reroll mechanics in 5E. There's already plenty of abilities and spells that allow a reroll, and depending on the DM, you could stack some of the other ones together, if RAW doesn't already state they have to use the new roll. Plus it feels really bad to roll a 2, spend the hit dice, and still roll a 2 on the 2nd try. I acknowledge there are different design philosophies, but I would much rather have a random bonus (based on the Hit Dice I expended), and possibly save a middling roll that could've succeeded. The slight alteration of: you can spend a Hit Die and roll it, adding a bonus equal to the number rolled. would be a good adjustment to make that possible.
Blood to Mana
As upset as I was with the Channel Divinity option, this one feels more disappointing. This is a direct copy of another feature Sorcerers already get at 2nd level, Flexible Casting, but using Hit Dice instead of an additional resource of Spell Points. This is the only feature that I think has no actual redeeming quality or reworkable aspects, because it's entirely unoriginal outside of the adjustment to the resource spent. This Domain capstone would need to be completely reworked in my opinion, and I have spent a bit of time thinking of something that would synergize with most of the previous features as well.
New: Blood Barrier
Whenever you expend any number of Hit Dice, you can choose one of those Hit Dice and gain 3 times the result of the rolled Hit Dice as Temporary HP. While you have Temporary HP gained from this feature, you have resistance to nonmagical Bludgeonning, Piercing, and Slashing damage.
This new feature is both untested and unbalanced, but I think it's definitely a step in the right direction for an impactful capstone feature, something that will heavily synergize with the theme of the class, but also keep with the frontline style the class has embodied through the features listed. I also personally like the bonus that it gives a small buffer to the damage you take from features like Tunnel Vision and most notably Channel Divinity: Sacrifice Self, possibly allowing the dice to let you have that glorious finale, but by the grace of your god, climb out of the rubble when everyone thinks you dead, and the DM didn't have to do anything but sit back and watch.
I want to say that this PDF didn't personally meet my standard for what I expected when reading "Sacrifice Domain", but what it did do was really get my gears going. I'm a person who normally leans towards DMing, but I haven't had a serious brainstorming session about designing a set of class features in a very long time, and it was a really fun experiment to take something I saw potential in, and loosely shape it into something I personally would want to play as a player, and something I'd be excited to see at the table as a DM. I truly do want to thank everyone involved in the production of this PDF, despite my (admittedly) harsh criticisms. I sincerely hope some of the rantings didn't come off too harsh, and that possibly I help with future productions or even just enhancing someone's time at the table.