Consider:
Memorial to Heroes - Land to get me some white dudes
* Kokusho - Great death triggers
Athreos
* Revel in Riches - Win con and ramp
* Smothering Tithe - Ramp and synergy with Revel
Swords to Plowshares - Cheap removal for when I can't get my engine online
Pawn of Ulamog - Only triggers off non-tokens
Mortify - Spot removal
Sidisi, Undead Vizier - Sac outlet, deathtouching blocker and a tutor
Sifter of Skulls - Pretty good death triggers
Carnival of Souls
Mind Stone - Cheap ramp that can cycle if I don't need it
Bloodghast - Recurrable sac fodder, but only once per turn usually
Diabolic Intent - Tutor and sac outlet in one
Kaya's Wrath
Memorial to Folly - Land to get back an important dude
Oketra's Monument – Slight ramp and token generation, but since I have relatively few white creature spells it's not really ramp, and I probably won't be casting creatures every turn either. Probably too minor
Reprocess - Could potentially draw a bunch of cards, but I might typically only sac one thing at a time
Open the Graves?
Mirror Entity - Great finisher with tokens and mana sink for Black Market
Meek Stone
Thaumatic Compass - Ramp and then a Maze of Ith
Xathrid Necromancer - I don't have a lot of humans, but it's potentially a good way to get back on board after a wipe. Also great with Increasing Devotion
Fell the Mighty - Semi-Plague Wind
Marshal's Anthem - Mass reanimate with an anthem
Faith's Reward - Sac my board with a Grave Pact effect up to clear the way, then get everything back?
Army of the Damned - Lots of black tokens
Blind Obedience - Don't let the big stuff block immediately
Cathars' Crusade - Great for winning with tokens or stuff that recurs
Elspeth, Knight-Errant - Reusable token generation
Enlightened Tutor - Get the second piece of Blasting Station/Darkest Hour combo
Ravos, Soultender - Anthem that I can't play in any other token decks, and a Raise Dead every turn
Sheoldred - They sac, I reanimate
Dread Return - Reanimation and potentially a sac outlet too
Skeletal Vampire - Get three bodies, and use extra mana to get more bats
Abhorrent Overlord - Potentially a bunch of black fliers
Martyr's Bond

Lands:
Desert of the Glorified
Desert of the True
Drifting Meadow
Emeria

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Considered cuts:
* Retribution of the Meek - 4 power might be too much for this to be relevant often
Secure the Wastes - Mana-intensive if I want to get actual value
Falkenrath Noble - A bit more mana than the other effects of this type
Ayli - How often will I have 50+ life? Sacrificing costs mana
Lingering Souls - Early tokens to get started with Scion, but not impressive, and not very interesting for Deathharmonicon

Suture Priest - Wincon with infinite loops, and ok otherwise, but not really on plan
Black Market
Dark Prophecy - Non-optional
Grim Haruspex - Only triggers off non-tokens
Grave Titan - Good value, but expensive and not very synergetic
Lightning Greaves - Do I have any single creature that really needs protecting? Teysa is important, but could be recast
Dusk // Dawn - Nice that it will spare a lot of my stuff, but expensive for a conditional sweeper. The back side is sweet, though
Victimize - Only works if I have two targets, and only works once, but reanimating two things and getting a sacrifice is gooood
Sadistic Hypnotist - Too mean?
Increasing Devotion - Gets lots of tokens for Scion, but not great for Deathharmonicon
Hidden Stockpile - Non-free sac outlet for a minor effect. The servo is nice, though
Spirit Bonds - Nice, added value with the possibility of protecting my stuff. Might be too hard on the whites to get full value of, though
Phyrexian Arena - Slow
Merciless Eviction - Don't want to exile my stuff, and this is kind of expensive
Darkest Hour + Blasting Station - Darkest Hour might be too good, and Blasting Station doesn't make sense without it

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Cuts:
Soul sisters - I don't have a lot of ways to utilize the life gain, and I'm not flooding the board with tokens, so they are probably not worth it
Burnished Hart - Expensive to use, both as ramp and as a sac outlet, and not very good as a sac outlet either.
Austere Command - Probably have enough board wipes and permanent removal that I don't need a 6 mana wipe
Charcoal Diamond - Replaced with a better ramp card (Sphere)
Legion's Landing - Expensive to use, and otherwise doesn't really do enough
Underworld Connections - Slow and mana intensive
Sorin, Solemn Visitor - The lifegain is nice, but might not be necessary, and the black tokens aren't that useful
Vampiric Rites - Expensive to use
Butcher of Malakir - Expensive and more fragile Grave Pact
Orzhov Cluestone - There are lots of better rocks
Orzhov Keyrune - There are better rocks. Can give some life or sacrifice fodder, though, which is nice
Costly Plunder - Trade in some fodder for a few cards at instant speed? Decent, but only works once
Windbrisk Heights - Don't have that many white creatures to reliably trigger this
Sorin, Lord of Innistrad - Better used in Edgar
Midnight Reaper - Not great with the token focus of Scion
Arcane Lighthouse - Expensive to activate