Activate Niko by paying {2} and tapping it, exiling Timestream Navigator and causing Shards you control to become a copy of Timestream Navigator until the end step.
Activate a Shard by paying {2}{U}{U}, tapping it and putting it from the battlefield onto the bottom of your library, causing you to take an extra turn after this one.
At the beginning of the next end step, Timestream Navigator is returned from exile to the battlefield. Soulherder then triggers, blinking Niko.
When Niko enters, it triggers, creating two Shard tokens.
Repeat each turn.

Infinite turns

Lock

Niko, Light of Hope

Timestream Navigator

Soulherder

Activate Niko by paying {1}{U}, blinking it.
When Niko enters, it and Deadeye Navigator's soulbond ability triggers.
Resolve the Niko trigger, creating two Shard tokens.
Resolve the Deadeye Navigator trigger, repairing it and Niko.
Activate the Shards by tapping them, adding {1}{U}.
Repeat.

Infinite artifact ETB

Infinite tapped artifact tokens

Infinite creature ETB

Infinite creature LTB

Infinite tapped Shard tokens

Deadeye Navigator

A Realm Reborn

Activate Emiel by paying {3}, blinking Niko.
When Niko enters, it triggers, creating two Shard tokens.
Activate the Shards by tapping them, adding {2}.
Activate Earthcraft by tapping Niko, untapping a basic land.
Activate the basic land by tapping it, adding {1}.
Repeat.

Emiel the Blessed

Earthcraft

Activate Emiel by paying {3}, blinking Niko.
When Niko enters, it triggers, creating two Shard tokens.
Activate the Shards by tapping them, adding {2}.
Activate Relic of Legends' second ability by tapping Niko, adding {1}.
Repeat.

Relic of Legends

Activate Emiel by paying {3}, blinking Niko.
When Niko enters, it triggers, creating two Shard tokens.
Activate Niko and the Shards by tapping them, adding {3}.
Repeat.

Combos with "Niko, Light of Hope"