Tap Scroll Rack and pay {1} to activate it, putting Part the Waterveil on top of your library.
Pass the turn.
On your next draw step, when you draw Part the Waterveil, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {2}{U}{U}, granting you an extra turn.

Infinite turns

Skip your draw step

God-Eternal Kefnet

Scroll Rack

Part the Waterveil

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

Panoptic Mirror

Activate Jace's zero loyalty ability, putting Part the Waterveil on top of your library.
Pass the turn.
On your next draw step, when you draw Part the Waterveil, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {2}{U}{U}, granting you an extra turn.

Jace, the Mind Sculptor

Cast Part the Waterveil for its awaken cost by paying {6}{U}{U}{U}, targeting a land you control.
Holding priority, cast Radiate by paying {3}{R}, creating a copy of Part the Waterveil targeting each other applicable land you control.
Resolve the first Part the Waterveil, causing you to take an extra turn after this one, put six +1/+1 counters on the targeted land and cause it to become a 0/0 Elemental creature until end of turn, and exile Part the Waterveil.
Repeat step 3 for each remaining Part the Waterveil.

Near-infinite turns

Radiate

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 Part the Waterveil by paying its mana cost.
Taigam triggers, copying Part the Waterveil and then exiling it with four time counters on it and giving it suspend.
Resolve the copy of Part the Waterveil, causing you to take an extra turn after this one.
Move to your next turn. At the beginning of that turn's upkeep, Part the Waterveil 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 Part the Waterveil 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 Part the Waterveil'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

Activate Mirror of Fate by tapping and sacrificing it.
Holding priority, activate Scrabbling Claws by tapping it, causing you to exile Mirror of Fate from your graveyard.
Resolve the Mirror of Fate ability, choosing itself, Part the Waterveil and three to five other cards, then exiling your library and putting the chosen cards on top, ensuring Part the Waterveil 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.
Move to your postcombat main phase.
Cast Part the Waterveil from exile without paying its mana cost, causing you to take an extra turn after this one and exile Part the Waterveil.
Cast Mirror of Fate from exile without paying its mana cost.
Repeat each turn.

Narset, Enlightened Master

Mirror of Fate

Scrabbling Claws

Cast Part the Waterveil by paying {4}{U}{U}.
Riku's first ability triggers - choose not to pay.
Holding priority, cast Narset's Reversal by paying {U}{U}, targeting Part the Waterveil.
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 Part the Waterveil, and returning the original Narset's Reversal to your hand.
Resolve the copy of Narset's Reversal created in step 5, copying Part the Waterveil and returning the original Part the Waterveil to your hand.
Resolve Part the Waterveil, causing you to take an extra turn after this one.
Repeat each turn.

Riku of Two Reflections

Narset's Reversal

Cast Part the Waterveil by paying {4}{U}{U}.
Saheeli triggers, creating a 1/1 Servo artifact creature token.
Resolve Part the Waterveil, causing you to take an extra turn after this one and exile it.
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 Part the Waterveil 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 Part the Waterveil being the top most card.
If Saheeli has less 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.
Move to your next turn, drawing Part the Waterveil during your draw step.
Repeat.

Saheeli, Sublime Artificer

Venser, the Sojourner

Cast the extra turn spell and move to your extra turn.
Activate Isochron Sceptre to cast Pull from Eternity, putting the extra turn spell from exile to your graveyard.
Attack with Backdraft Hellkite to give your extra turn flashback, then cast it.
Repeat for infinite turns.

Isochron Scepter

Pull from Eternity

Backdraft Hellkite

Cast Part the Waterveil by paying its mana cost.
Taigam triggers, copying Part the Waterveil and exiling the original Part the Waterveil with four time counters on it.
Resolve the Part the Waterveil copy, causing you to take an extra turn after this one.
Cast Clockspinning with buyback by paying {3}{U}, removing a time counter from Part the Waterveil and returning Clockspinning to your hand.
Repeat step 4 one additional time.
Move to your next turn. At the beginning of your upkeep, Part the Waterveil's suspend ability triggers, removing a time counter from it.
Cast Clockspinning with buyback by paying {3}{U}, removing a time counter from Part the Waterveil and returning Clockspinning to your hand.
Part the Waterveil'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 Part the Waterveil by paying {4}{U}{U}.
Saheeli triggers, creating a 1/1 Servo artifact creature token.
Resolve Part the Waterveil, 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 Part the Waterveil 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 Part the Waterveil being the top most card.
Move to your next turn, drawing Part the Waterveil during your draw step.
Repeat.

Contagion Engine

Declare Fire Lord Azula as an attacker, triggering its firebending ability, adding {R}{R}.
Holding priority, cast Part the Waterveil by paying its mana cost.
Fire Lord Azula's second ability triggers, copying Part the Waterveil.
Holding priority, cast Narset's Reversal by paying {U}{U}, targeting the original Part the Waterveil 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 Part the Waterveil spell, and then return the original Narset's Reversal to your hand.
Resolve the copy of Narset's Reversal, copying Part the Waterveil and returning the original Part the Waterveil to your hand.
Resolve both copies of Part the Waterveil 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 Part the Waterveil by paying its mana cost.
Holding priority, cast Narset's Reversal by paying {U}{U}, targeting Part the Waterveil.
Holding priority, activate Slick Imitator by paying {1} and sacrificing it, copying 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 Part the Waterveil, and returning the original Narset's Reversal to your hand.
Resolve Part the Waterveil, causing you to take an extra turn after this one.
Cast Slick Imitator from your graveyard by paying {1}{U}.
Repeat each turn.

Muldrotha, the Gravetide

Slick Imitator

Deal combat damage to an opponent using Efreet Flamepainter.
Efreet Flamepainter triggers, causing you to cast Part the Waterveil from your graveyard without paying its mana cost.
Resolve Part the Waterveil, causing you to take an extra turn after this one and exile it.
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 Part the Waterveil from exile into your graveyard.
Repeat each turn.

Efreet Flamepainter

Cast Part the Waterveil by paying {4}{U}{U}, causing you to take an extra turn after this one and exile Part the Waterveil.
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 Part the Waterveil into your graveyard from exile.
Move to your next turn.
Activate Dralnu by tapping it, giving Part the Waterveil flashback until end of turn.
Cast Part the Waterveil from your graveyard by paying {4}{U}{U}, causing you to take an extra turn after this one and exile Part the Waterveil.
Repeat from step 2.

Dralnu, Lich Lord

Karador, Ghost Chieftain

Cast Part the Waterveil by paying {4}{U}{U}, causing you to take an extra turn after this one and exile Part the Waterveil.
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 Part the Waterveil into your graveyard from exile.
Move to your next turn.
Cast Part the Waterveil from your graveyard by paying {4}{U}{U}, causing you to take an extra turn after this one and exile Part the Waterveil.
Repeat from step 2.

Combos with "Part the Waterveil"