If Rousing Refrain is in your hand, cast it by paying {3}{R}{R}.
Otherwise, activate The Tenth Doctor by paying {7}, causing you to time travel three times, removing all time counters from Rousing Refrain and cast Rousing Refrain from exile without paying its mana cost.
Resolve Rousing Refrain, adding at least seven {R}, and exiling Rousing Refrain with three time counters on it.
Repeat from step 2.
If an opponent has eight or more cards in hand, this combo nets infinite red mana.

Infinite magecraft triggers

Infinite storm count

The Tenth Doctor

Rousing Refrain

Active Rift Elemental by paying {1}{R} and removing a time counter from Rousing Refrain.
Repeat until Rousing Refrain has no time counters on it.
Rousing Refrain triggers, causing you to cast it without paying its mana cost.
Resolve Rousing Refrain, adding at least seven {R} and exiling Rousing Refrain with three time counters on it.
Resolve all Rift Elemental abilities from step 1, giving Rift Elemental +2/+0 for each ability resolved.
Repeat.

Infinitely powerful creature until end of turn

Infinite red mana

Rift Elemental

Cast Rousing Refrain by paying its mana cost
Holding priority, cast Reiterate with buyback by paying {4}{R}{R}, creating a copy of Rousing Refrain and returning Reiterate to your hand.
Resolve the copy of Rousing Refrain, adding at least six {R}.
Repeat from step 2.

Reiterate

If Rousing Refrain is in your hand, cast it by paying its mana cost. Otherwise, at the beginning of your upkeep, its suspend ability will trigger, removing the final time counter from it and casting it from exile without paying its mana cost.
Holding priority, activate Pili-Pala by paying {R} and tapping it, copying Rousing Refrain.
Resolve the copy of Rousing Refrain, adding at least {R}{R}
Activate Pili-Pala by paying {2} and untapping it, adding one mana of any color.
Repeat from step 2.

Infinite colored mana

Pili-Pala

Dual Casting

Cast Rousing Refrain by paying {3}{R}{R}, targeting an opponent with at least four cards in their hand.
Holding priority, activate Emiel by paying {3}, blinking Dualcaster Mage.
Dualcaster Mage enters the battlefield, copying Rousing Refrain.
Resolve the copy of Rousing Refrain, adding at least {R}{R}{R}{R}.
Repeat from step 2.

Infinite blinking

Infinite creature ETB

Infinite creature LTB

Dualcaster Mage

Emiel the Blessed

Cast Rousing Refrain by paying {3}{R}{R}.
Holding priority, activate Emiel by paying {3}, blinking Naru Meha.
When Naru Meha enters the battlefield, it triggers, copying Rousing Refrain.
Resolve the copy of Rousing Refrain, adding at least {R}{R}{R}.
Repeat from step 2.
If an opponent has at least four cards in hand, this combo nets infinite red mana.

Combos with "Rousing Refrain"