Activate five lands by tapping them, adding at least {5}.
Heartbeat of Spring triggers five times, adding at least {5}.
Activate Magus of the Candelabra by paying {5} and tapping it, untapping five lands.
Activate Staff of Domination's third ability by paying {3} and tapping it, untapping Magus of the Candelabra.
Activate Staff of Domination's first ability by paying {1}, untapping Staff of Domination.
Repeat.
Once you have infinite mana, you may use it to activate Staff of Domination's other abilities.

Infinite card draw

Infinite draw triggers

Infinite lifegain

Infinite lifegain triggers

Infinite mana creatures you control can produce

Infinite mana lands you control can produce

Infinite untap of creatures you control

Infinite untap of lands you control

Magus of the Candelabra

Staff of Domination

Heartbeat of Spring

Activate two lands by tapping them, adding at least {2}.
Heartbeat of Spring triggers twice, adding {2}.
Activate Magus of the Candelabra by paying {3} and tapping it, untapping the two lands and Magus of the Candelabra.
Repeat.

Infinite green mana

Ashaya, Soul of the Wild

Activate Pili-Pala by tapping it, adding {G}{G}.
Activate Pili-Pala by paying {2} and untapping it, adding one mana of any color.
Repeat.

Infinite colored mana

Pili-Pala

Play a land. When the land enters, Springheart Nantuko triggers, causing you to pay {1}{G} to create a token copy of Dryad Arbor.
When the Dryad Arbor token enters, Springheart Nantuko triggers. Holding priority, activate the Dryad Arbor token by tapping it, adding {G}.
Heartbeat of Spring triggers, adding {G}.
Resolve the Springheart Nantuko trigger, causing you to pay {1}{G} to create a token copy of Dryad Arbor.
Repeat from step 2.

Infinite ETB

Infinite tapped creature tokens

Infinite landfall triggers

Infinite tapped Forest tokens

Springheart Nantuko

Dryad Arbor

Concordant Crossroads

Activate Fertilid, searching your library for a basic Forest card, putting it onto the battlefield tapped.
Amulet of Vigor triggers, untapping the land.
Retreat to Kazandu triggers, putting a +1/+1 counter Fertilid.
Tap the land for {G}{G}.
Repeat.

Near-infinite landfall triggers

Put all basic Forests from your library onto the battlefield

Fertilid

Amulet of Vigor

Retreat to Kazandu

Activate Fertilid, searching your library for a basic Forest card, putting it onto the battlefield tapped.
Amulet of Vigor triggers, untapping the land.
Felidar Retreat triggers.
Resolve the Felidar Retreat trigger putting a +1/+1 counter on each creature you control.
Tap the land for {G}{G}.
Repeat.

Near-infinite +1/+1 counters on creatures you control

Felidar Retreat

Activate Karn by paying {1}, causing Basalt Monolith to become an artifact creature until end of turn.
Activate Basalt Monolith's first ability by tapping it, adding {C}{C}{C}.
Heartbeat of Spring triggers, adding {C}.
Activate Basalt Monolith's second ability by paying {3}, untapping it.
Repeat from step 2.

Infinite colorless mana

Karn, Silver Golem

Basalt Monolith

Activate Staff of Domination by tapping it, adding {B} as it's a Swamp land due to Toph and Urborg
Heartbeat of Spring triggers, adding {B}.
Activate Staff of Domination's first ability by paying {1}, untapping it.
Repeat.

Infinite black mana

Toph, the First Metalbender

Urborg, Tomb of Yawgmoth

Activate Staff of Domination by tapping it, adding {G} as it's a Forest land due to Toph and Yavimaya.
Heartbeat of Spring triggers, adding {G}.
Activate Staff of Domination's first ability by paying {1}, untapping it.
Repeat.

Yavimaya, Cradle of Growth

Combos with "Heartbeat of Spring"