Activate Viscera Seer by sacrificing Reassembling Skeleton.
When Reassembling Skeleton dies, Pitiless Plunderer and Rat King trigger, creating a creature token and a Treasure token.
Resolve the Viscera Seer ability.
Activate Viscera Seer by sacrificing the creature token.
When the creature token dies, Pitiless Plunderer triggers, creating a Treasure token.
Resolve the Viscera Seer ability.
Activate the Treasures by tapping and sacrificing them, adding {1}{B}.
Activate Reassembling Skeleton by paying {1}{B}, returning it from your graveyard to the battlefield.
Repeat.

Infinite artifact ETB

Infinite artifact LTB

Infinite artifact sacrifice triggers

Infinite creature ETB

Infinite creature LTB

Infinite death triggers

Infinite creature sacrifice triggers

Infinite scry 1

Viscera Seer

Reassembling Skeleton

Pitiless Plunderer

Rat King, Pale Piper

Activate Phyrexian Altar by sacrificing Nether Traitor, adding {B}.
When Nether Traitor dies, Rat King triggers, creating a creature token.
Activate Phyrexian Altar by sacrificing the creature token, adding one mana of any color.
When the creature token dies, Nether Traitor triggers, causing you to pay {B} to return Nether Traitor from your graveyard to the battlefield.
Repeat.

Infinite colored mana

Nether Traitor

Phyrexian Altar

Activate Phyrexian Altar by sacrificing Ozox, adding {1}.
When Ozox dies, it and Rat King trigger.
Resolve the Ozox trigger, creating a legendary 2/1 Jumblebones creature token.
Resolve the Rat King trigger, creating a creature token.
Activate Phyrexian Altar twice by sacrificing Jumblebones and the other creature token, adding {1}{B}.
When Jumblebones dies, it triggers, returning Ozox from your graveyard to your hand.
Cast Ozox by paying {2}{B}.
Repeat.

Infinite storm count

Ozox, the Clattering King

Activate Phyrexian Altar by sacrificing Oathsworn Vampire, adding {B}.
When Oathsworn Vampire dies, Rat King triggers, creating a creature token.
Activate Phyrexian Altar by sacrificing the creature token, adding {1}.
Cast Oathsworn Vampire from your graveyard by paying {1}{B}.
Repeat.

Oathsworn Vampire

Activate Umbral Collar Zealot by sacrificing another nonland creature.
When the creature dies, Beifong's Bounty Hunters triggers, earthbending a land you control.
Resolve the Umbral Collar Zealot ability.
Activate Umbral Collar Zealot by sacrificing the earthbent land.
When the land dies, Rat King and Beifong's Bounty Hunters trigger.
Resolve the Beifong's Bounty Hunters trigger, returning the land from your graveyard to the battlefield.
Resolve the Rat King trigger, creating a creature token.
Resolve the Umbral Collar Zealot ability.
Repeat.

Infinite landfall triggers

Infinite surveil

Beifong's Bounty Hunters

Umbral Collar Zealot

Activate Viscera Seer by sacrificing Tenacious Dead.
When Tenacious Dead dies, it, Rat King, and Pitiless Plunderer trigger.
Resolve the Pitiless Plunderer trigger, creating a Treasure token.
Resolve the Rat King trigger, creating a creature token.
In response to the remaining trigger, activate Viscera Seer by sacrificing the creature token.
When the creature token dies, Pitiless Plunderer triggers, creating a Treasure token.
Resolve the Viscera Seer ability from step 5.
Activate two Treasure tokens by tapping and sacrificing them, adding {B}{B}.
Resolve the Tenacious Dead trigger, paying {1}{B} to return it to the battlefield from your graveyard.
Resolve the Viscera Seer ability from step 1.
Repeat.

Tenacious Dead

Cast Traitorous Greed by paying {3}{R}.
Forum Necroscribe triggers, returning Living Lightning from your graveyard to the battlefield.
Resolve Traitorous Greed, untapping Priest of the Forgotten Gods, giving it haste until end of turn, and adding {R}{R}.
Activate Priest of the Forgotten Gods by tapping it, sacrificing Living Lightning and any creature not part of the combo.
When Living Lightning dies, it and Rat King triggers.
Resolve the Living Lightning trigger, returning Traitorous Greed from your graveyard to your hand.
Resolve the Rat King trigger, creating a creature token.
Resolve the Priest of the Forgotten Gods ability, causing any number of opponents to sacrifice a creature and lose 2 life, adding {B}{B}, and drawing a card.
Repeat, sacrificing the newly created token in step 4 instead of the additional creature.

Each opponent sacrifices nearly infinite creatures

Infinite card draw

Infinite draw triggers

Near-infinite creature ETB

Near-infinite creature LTB

Near-infinite death triggers

Near-infinite lifeloss

Near-infinite creature sacrifice triggers

Near-infinite storm count

Forum Necroscribe

Priest of Forgotten Gods

Traitorous Greed

Living Lightning

Activate Phyrexian Altar by sacrificing Squee, adding {R}.
When Squee dies, Rat King triggers, creating a creature token.
Activate Phyrexian Altar by sacrificing the creature token, adding {R}.
Cast Squee from your graveyard by paying {R}{R} due to Green Goblin.
Repeat.

Norman Osborn // Green Goblin

Squee, the Immortal

Cast Ebondeath from your graveyard by paying {B}{B} due to Green Goblin.
Activate Phyrexian Altar by sacrificing Ebondeath, adding {B}.
When Ebondeath dies, Rat King triggers, creating a creature token.
Activate Phyrexian Altar by sacrificing the creature token, adding {B}.
Repeat.

Ebondeath, Dracolich

Combos with "Rat King, Pale Piper"