Viscera Seer - one of the most important creatures in the deck. Not only is it a sacrifice outlet that can come down early. The ability to scry is extremely important, as this deck can run out of gas if you draw the wrong combination of spells
Doomed Traveler - pretty much just sacrifice fodder, giving you essentially two creatures for one mana in this deck. It can also get in for some damage early game because the opponent doesn't want to kill it because you'll just get a better creature
Cartel Aristocrat - another great sacrifice outlet. This card is great for chipping away at the opponents life total, and is a great chump blocker as long as you have another creature to sac. This card is played in every aristocrats deck and for good reason. The one downside is you can't sac it to itself like with other sacrifice outlets, but that rarely becomes an issue
Bloodthrone Vampire - just another way to sacrifice creatures. It's not the best, but I'd rather have more sac outlets than less, and this card can sometimes close it games by itself if it gets big enough
Blood Artist and Zulaport Cutthroat - the cards that make this deck work so well, and often how you'll kill the opponent. The ability to sacrifice a creature for a 2 point life total swing is hard to beat. And when you get more than one of these out it's hard for the opponent to do anything. Always a good draw with a sacrifice outlet on the battlefield
Tidehollow Sculler - a bit of control and hand disruption to take threats away that you wouldn't otherwise be able to deal with. You can also do the trick to sacrifice it in response to the first trigger to exile the card forever. I've gone back and forth on whether to use this or Inquisition of Kozilek, but I think this is the right choice because it's a creature to sac, and you have better things to do on turn one
Geralf's Messenger - Really one of the all-stars of this deck. With a sacrifice outlet, this immediately deals 4 damage to the opponent, and with blood artists in play that can be 5 or more life, which can catch an opponent off guard and really swing the game in your favor. And as I'll touch on later, there's no trouble playing this on turn three
Tragic Slip - a bit of unconventional removal, but in this deck it's one of the best options available. You're almost always going activate the morbid trigger, making this better than Fatal Push, getting around indestructible and regenerate. I also take this over Path to Exile because it doesn't exile which is another death trigger for blood artist
Lingering Souls - really powerful card in this deck. It gives you 4 creatures to sac, and those creatures can also close out the game if the opponent doesn't have an answer
Rally the Ancestors - the namesake card and for good reason. This card really gives you the extra push if you're behind, bringing back all your creatures. It essentially gives you double the death triggers, and with Blood Artists and Geralf's Messengers, this will quickly close the game. Usually when this card is played, the game is about to be over. I only run 3 copies because you only really want to see 1 at most per game, and they can get redundant
Westvale Abbey - a utility land that occasionally gives you creatures if you need them, but I use that ability pretty rarely. This card shines with the second ability, giving you a huge threat if your missing a piece such as a sac outlet