At the beginning of your upkeep, Panoptic Mirror triggers, casting a copy of Alrund's Epiphany without paying its mana cost.
Resolve Alrund's Epiphany, causing you to take an extra turn after this one.
Repeat each turn.

Infinite turns

Panoptic Mirror

Alrund's Epiphany

Cast the self-suspending card by paying its mana cost if its in your hand, or any other spell otherwise if you have not cast a spell this turn.
Cast Alrund's Epiphany by paying its mana cost.
Taigam triggers, copying Alrund's Epiphany and then exiling it with four time counters on it and giving it suspend.
Resolve the copy of Alrund's Epiphany, causing you to take an extra turn after this one.
Move to your next turn. At the beginning of that turn's upkeep, Alrund's Epiphany and the self-suspending card's suspend abilities trigger, removing a time counter from each of them.
Activate The Tenth Doctor by paying {7}, removing three time counters from Alrund's Epiphany and the self-suspending card, triggering their suspend abilities.
Resolve the self-suspending card's suspend trigger, causing you to cast it from exile without paying its mana cost, and eventually exile it with time counters on it.
Resolve the Alrund's Epiphany's suspend trigger, causing you to cast it from exile without paying its mana cost.
Repeat from step 3.

Self-Suspending Instant or Sorcery

The Tenth Doctor

Taigam, Master Opportunist

Cast Alrund's Epiphany by paying {5}{U}{U}.
Riku's first ability triggers - choose not to pay.
Holding priority, cast Narset's Reversal by paying {U}{U}, targeting Alrund's Epiphany.
Riku's first ability triggers, causing you to pay {U}{R} to copy Narset's Reversal, with the copy targeting the original Narset's Reversal.
Resolve the copy of Narset's Reversal, copying the original Narset's Reversal targeting Alrund's Epiphany, and returning the original Narset's Reversal to your hand.
Resolve the copy of Narset's Reversal created in step 5, copying Alrund's Epiphany and returning the original Alrund's Epiphany to your hand.
Resolve Alrund's Epiphany, causing you to take an extra turn after this one.
Repeat each turn.

Riku of Two Reflections

Narset's Reversal

Activate Mirror of Fate by tapping and sacrificing it.
Holding priority, activate Scrabbling Claws's first ability by tapping it, exiling Mirror of Fate from your graveyard.
Resolve the Mirror of Fate ability, choosing itself, Alrund's Epiphany and three to five other face-up cards you own in exile, then exiling your library and putting the chosen cards on top, ensuring Alrund's Epiphany and Mirror of Fate are the topmost cards.
Declare Narset as an attacker.
Narset triggers, exiling the top four cards of your library and allowing you to cast them from exile this turn without paying their mana costs.
During your postcombat main phase, cast Alrund's Epiphany from exile without paying its mana cost, causing you to create two 1/1 Bird creature tokens, take an extra turn after this one and exile Alrund's Epiphany.
Cast Mirror of Fate from exile without paying its mana cost.
Repeat each turn.

Narset, Enlightened Master

Mirror of Fate

Scrabbling Claws

Cast Alrund's Epiphany by paying {5}{U}{U}.
Saheeli triggers, creating a 1/1 Servo artifact creature token.
Resolve Alrund's Epiphany, causing you to create two 1/1 Bird creature tokens, take an extra turn after this one and exile Alrund's Epiphany.
Activate Saheeli by removing two loyalty counters from it, causing the Servo to become a copy of Mirror of Fate until end of turn.
Activate the Servo by tapping and sacrificing it, choosing Alrund's Epiphany and up to six other cards face up in exile, then exiling your library and putting the chosen cards on top of your library, with Alrund's Epiphany being the topmost card.
If Saheeli has fewer than three loyalty counters on it, activate Venser's first loyalty ability by putting two loyalty counters on it, exiling Saheeli until your next end step.
At the beginning of your end step, if you activated Venser's ability, Venser triggers, returning Saheeli from exile to the battlefield.
Repeat each turn, drawing Alrund's Epiphany during your draw step.

Saheeli, Sublime Artificer

Venser, the Sojourner

Declare Fire Lord Azula as an attacker, triggering its firebending ability, adding {R}{R}.
Holding priority, cast Alrund's Epiphany by paying its mana cost.
Fire Lord Azula's second ability triggers, copying Alrund's Epiphany.
Holding priority, cast Narset's Reversal by paying {U}{U}, targeting the original Alrund's Epiphany spell.
Fire Lord Azula's second ability triggers, copying Narset's Reversal, targeting the original Narset's Reversal.
Resolve the copy of Narset's Reversal, causing you to copy Narset's Reversal targeting the original Alrund's Epiphany spell, and then return the original Narset's Reversal to your hand.
Resolve the copy of Narset's Reversal, copying Alrund's Epiphany and returning the original Alrund's Epiphany to your hand.
Resolve both copies of Alrund's Epiphany from steps 3 and 7, causing you to take two extra turns after this one.
Repeat during your second extra turn.

Fire Lord Azula

Valley Floodcaller

Cast Alrund's Epiphany by paying its mana cost.
Taigam triggers, copying Alrund's Epiphany and exiling the original Alrund's Epiphany with four time counters on it.
Resolve the Alrund's Epiphany copy, causing you to take an extra turn after this one.
Cast Clockspinning with buyback by paying {3}{U}, removing a time counter from Alrund's Epiphany and returning Clockspinning to your hand.
Repeat step 4 one additional time.
Move to your next turn. At the beginning of your upkeep, Alrund's Epiphany's suspend ability triggers, removing a time counter from it.
Cast Clockspinning with buyback by paying {3}{U}, removing a time counter from Alrund's Epiphany and returning Clockspinning to your hand.
Alrund's Epiphany's suspend ability triggers, causing you to cast it from exile without paying its mana cost.
Repeat from step 2.

Taigam, Master Oppurtunist

Clockspinning

Cast Alrund's Epiphany by paying {5}{U}{U}.
Saheeli triggers, creating a 1/1 Servo artifact creature token.
Resolve Alrund's Epiphany, causing you to take an extra turn after this one and exile it.
Activate Contagion Engine by paying {6} and tapping it, putting two loyalty counters on Saheeli.
Activate Saheeli by removing two loyalty counters from it, causing the Servo to become a copy of Mirror of Fate until end of turn.
Activate the Servo by tapping and sacrificing it, choosing Alrund's Epiphany and up to six other cards face up in exile, then exiling your library and putting the chosen cards on top of your library, with Alrund's Epiphany being the top most card.
Move to your next turn, drawing Alrund's Epiphany during your draw step.
Repeat.

Skip your draw step

Contagion Engine

Deal combat damage to an opponent using Efreet Flamepainter.
Efreet Flamepainter triggers, causing you to cast Alrund's Epiphany from your graveyard without paying its mana cost.
Resolve Alrund's Epiphany, causing you to create two 1/1 Bird creature tokens, take an extra turn after this one and exile Alrund's Epiphany.
Activate Isochron Scepter by paying {2} and tapping it, casting a copy of Pull from Eternity without paying its mana cost.
Resolve Pull from Eternity, putting Alrund's Epiphany from exile into your graveyard.
Repeat each turn.

Combos with "Alrund's Epiphany"