1)
Mitotic Slime OR
Grave Titan OR
Worldspine Wurm +
Nim Deathmantle + [card]Ashnod's Altar[/card] = infinite tokens. With Mitotic Slime, you can produce infinite 2/2 tokens that produce infinite 1/1 tokens when they die should a player wipe the board before you alpha strike. With Worldspine Wurm, you sacrifice it with Ashnod's Altar to produce two colorless, put the Nim Deathmantle trigger on top of the stack, then sacrifice a 5/5 Wurm token to pay the additional two colorless mana required of the trigger, then repeat. You'll end up with infinite 5/5 Wurms and you'll shuffle Worldspine Wurm into your library.
+ [card:
s0x1udiu]Blood Artist[/card] = deal infinite damage to everyone
+
Harvester of Souls or
Soul of the Harvest = draw a ton of cards.
2)
Mikaeus, the Unhallowed +
Nim Deathmantle + [card]Ashnod's Altar[/card] + any creature with an ETB or LTB ability = trigger the ETB or LTB ability infinitely. How it works: sacrifice the creature to Ashnod's Altar, put the undying trigger at the top of the stack, declare creature's ETB or LTB ability, sacrifice it again in response to the trigger, use the four floating mana to equip Nim Deathmantle to the creature, declare the ETB or LTB ability, then repeat. This is the most degenerate combo in the deck and allows you to do some silly things, like draw all the land out of your deck (
Yavimaya Elder), kill every nonartifact, nonblack creature ([card]
Shriekmaw[/card],
Bone Shredder), destroy all opponents' artifacts, enchantments, and lands (
Acidic Slime), deal infinite damage to everyone (
Blood Artist), or, with Savra,
Grave Pact, or
Butcher of Malakir out, completely decimate every opponent's board and gain infinite life (
Terastodon) while leaving them with no 3/3 tokens. If you have one black mana open and a nontoken creature on the board, you can also use
Disciple of Bolas to gain infinite life, draw your deck, then cast
Blood Artist and deal infinite damage for the win.
+
Harvester of Souls OR
Soul of the Harvest = draw your deck, again with the intention of drawing into Blood Artist to cast it and
win on your turn.
+ Savra = each opponent sacrifices half as many creatures as you sacrifice if the creature is typically green, and exacly as many creatures as you sacrifice if it is typically black (creatures are black when equipped with Nim Deathmantle, which is exactly half the amount of times you sacrifice it if the creature is typically green). You end up losing no life if the creature is typically green, but pay two life for each trigger if it's typically black. Note that Savra being in this combo along with any green creature you're sacrificing will give you infinite life, even if it is Acidic Slime since you don't have to kill your own Nim Deathmantle, enchantments, and lands until you terminate the loop (sacrifice Acidic Slime in response to the ETB trigger each time).
+
Butcher of Malakir OR
Grave Pact = each opponent sacrifices as many creatures as you sacrifice your ETB/LTB creature.
3) [card:
s0x1udiu]Living Death[/card] +
Grave Pact OR
Butcher of Malakir = make everyone sacrifice as many creatures as you sacrificed to Living Death after it resolves.
+ Savra and a few black creatures on your board before casting = extra lulz.
+
Flesh Allergy in a multiplayer game = pretty much kill whoever you think deserves to die the most.
4)
Living Death + [card]Ashnod's Altar[/card] = sacrifice all your creatures before casting Living Death or with Living Death on the stack to make colorless mana and get all your nontoken creatures back.
5)
Living Death +
Mikaeus, the Unhallowed on board before casting = get all the nontoken creatures you sacrificed back with +1/+1 counters except for Mikaeus.
6)
Living Death + [card]Grave Betrayal[/
card] = take control of all nontoken creatures sacrificed by your opponents to Living Death at your end step.
7)
Living Death +
Gleancrawler in your graveyard = put all creatures you sacrificed to Living Death in your hand at the end of your turn.
Necrogenesis + [card]Ashnod's Altar[/card] = exile creatures from all opponents' graveyards and make a 1/1 green token.
+ Savra = gain two life for each creature card exiled.
+
Grave Pact OR
Butcher of Malakir = each opponent sacrifices a creature for each creature card exiled.
9)
Mikaeus, the Unhallowed +
Fleshbag Marauder OR
Slum Reaper = each player sacrifices two
creatures.
+ Savra OR
Grave Pact OR
Butcher of Malakir = each player sacrifices four creatures. With Savra, you lose four life.
10)
Mikaeus, the Unhallowed +
Birthing Pod = keep the creature you sacrifice to Birthing Pod if it's a nontoken creature.
11)
Woodfall Primus + [card]Ashnod's Altar[/card] +
Mikaeus, the Unhallowed OR
Nim Deathmantle = destroy as many noncreature permanents as you see fit.
12)
Faceless Butcher + any sac outlet = permanently exile a creature.
+
Mimic Vat = permanently exile a creature each turn.