Activate Aetherflux Resevoir by paying 50 life, targeting yourself, but instead preventing the damage and causing you to gain 100 life due to Purity.
Repeat an arbitrarily large number of times.
Activate Aetherflux Resevoir by paying 50 life, dealing 50 damage to any target.
Repeat step 3 as desired.

Infinite damage

Infinite lifegain

Infinite lifegain triggers

Aetherflux Reservoir

Purity

Rhox Faithmender

Increase Atla's toughness by at least one.
Activate Mirror Entity an arbitrarily large number of times by paying a total of {0}.
Resolve the first Mirror Entity ability, causing all creatures you control to have base power and toughness 0/0 and gain all creature types until end of turn.
All creatures you control except Atla die as a state-based action due to having zero toughness.
If Purity died this way, it triggers, shuffling itself into your library.
Atla triggers once for each creature that died.
Resolve the first Atla trigger, revealing cards from the top of your library until you reveal a creature card, then putting the creature card onto the battlefield and all other revealed cards on the bottom of your library.
Repeat step 7 for each remaining Atla trigger.
Repeat from step 3 for each remaining Mirror Entity ability.

Infinite death triggers

Infinite ETB

Infinite LTB

Atla Palani, Nest Tender

Mirror Entity

Cast Wheel of Misfortune by paying {2}{R}, choosing an arbitrarily large number, and causing you to gain life equal to the number you chose due to Purity if you chose the largest number.
If you didn't choose the largest number, Wheel of Misfortune deals that much damage to each opponent who chose the largest number.

Near-infinite lifegain

Wheel of Misfortune

Activate Aetherflux Resevoir by paying fifty life, targeting yourself and causing you to gain 150 life due to Purity and Fiery Emancipation.
Repeat an arbitrarily large number of times.
Activate Aetherflux Resevoir by paying fifty life, dealing 150 damage to any target.
Repeat step 3.

Fiery Emancipation

Activate Aetherflux Resevoir by paying fifty life, targeting yourself and causing you to gain 100 life due to Purity and Dictate of the Twin Gods.
Repeat an arbitrarily large number of times.
Activate Aetherflux Resevoir by paying fifty life, dealing 100 damage to any target.
Repeat step 3.

Dictate of the Twin Gods

Activate Aetherflux Resevoir by paying fifty life, targeting yourself and causing you to gain 100 life due to Purity and Furnace of Rath.
Repeat an arbitrarily large number of times.
Activate Aetherflux Resevoir by paying fifty life, dealing 100 damage to any target.
Repeat step 3.

Furnace of Rath

Activate Aetherflux Resevoir by paying fifty life, targeting yourself and causing you to gain 150 life due to Purity and City on Fire.
Repeat an arbitrarily large number of times.
Activate Aetherflux Resevoir by paying fifty life, dealing fifty damage to any target.
Repeat step 3.

City on Fire

Activate Aetherflux Resevoir by paying fifty life, targeting yourself and causing you to gain 100 life due to Purity and Curse of Bloodletting.
Repeat an arbitrarily large number of times.
Activate Aetherflux Resevoir by paying fifty life, dealing fifty damage to any target.
Repeat step 3.

Curse of Bloodletting

Activate Aetherflux Resevoir by paying fifty life, targeting yourself and causing you to gain 100 life due to Purity and Angrath's Marauders.
Repeat an arbitrarily large number of times.
Activate Aetherflux Resevoir by paying fifty life, dealing fifty damage to any target.
Repeat step 3.

Angrath's Marauders

Activate Ashnod's Altar by sacrificing Purity, adding {C}{C}.
Purity and Verdant Succession trigger.
Resolve the Purity trigger, shuffling it into your library.
Resolve the Verdant Succession trigger, searching your library for Purity, putting it onto the battlefield and shuffling your library.
Repeat.

Infinite colorless mana

Infinite sacrifice triggers

Verdant Succession

Ashnod's Altar

Painter's Servant

Activate Altar of Dementia by sacrificing Purity.
Purity and Verdant Succession trigger.
Resolve the Purity trigger, shuffling it into your library.
Resolve the Verdant Succession trigger, searching your library for Purity, putting it onto the battlefield and shuffling your library.
Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to Purity's power.
Repeat.

Infinite mill

Infinite self-mill

Altar of Dementia

Activate Phyrexian Altar by sacrificing Purity, adding one mana of any color.
Purity and Verdant Succession trigger.
Resolve the Purity trigger, shuffling it into your library.
Resolve the Verdant Succession trigger, searching your library for Purity, putting it onto the battlefield and shuffling your library.
Repeat.

Infinite colored mana

Phyrexian Altar

At the beginning of your upkeep, Descent into Avernus triggers, putting two descent counters on it, then causing each player to create a number of Treasure tokens equal to the number of descent counters on Descent into Avernus, causing each opponent to be dealt an amount of damage equal to the number of descent counters on Descent into Avernus, and causing you to gain life equal to the number of descent counters on Descent into Avernus.
Activate Time Sieve by tapping it and sacrificing five Treasures, causing you to take an extra turn after this one.
Repeat each turn.

Infinite turns

Time Sieve

Descent into Avernus

Cause a creature to enter the battlefield under your control by any method.
When that creature enters the battlefield, Reaper King triggers, destroying that creature.
Resolve Atla Palani's trigger, revealing cards from the top of your library until you reveal a creature card and putting it onto the battlefield.
Repeat from step 2 until Purity enters the battlefield then dies, or until you choose to end the loop by destroying an opponent's permanent.
If Purity dies, it and Atla Palani trigger.
Resolve Purity's trigger, shuffling it into your library.
Continue from step 3.

Combos with "Purity"