Pay {1}{U} to exile and return Omnath to the battlefield.
Soulbond Omnath with Deadeye Navigator.
Omnath enters, triggering its own landfall ability twice, drawing a card, gaining 4 life, and adding {U}{R}{W}{G}.
Repeat.

Infinite card draw

Infinite ETB

Infinite landfall triggers

Infinite LTB

Near-infinite green mana

Near-infinite lifegain

Near-infinite lifegain triggers

Near-infinite red mana

Near-infinite white mana

Omnath, Locus of Creation

Ancient Greenwarden

Ashaya, Soul of the Wild

Deadeye Navigator

Cast Ghostly Flicker by paying {2}{U}, blinking Omnath and Mystic Sanctuary.
Omnath and Mystic Sanctuary enter the battlefield, triggering Mystic Sanctuary, Omnath's first ability and Omnath's second ability twice.
Resolve the Mystic Sanctuary trigger, putting Ghostly Flicker on top of your library from your graveyard.
Resolve all Omnath triggers, causing you to draw a card, gain four life and add {R}{G}{W}{U}.
Repeat.

Infinite blue mana

Infinite draw triggers

Infinite green mana

Infinite lifegain

Infinite lifegain triggers

Infinite magecraft triggers

Infinite red mana

Infinite storm count

Infinite white mana

Ghostly Flicker

Mystic Sanctuary

Cast Doppelgang by paying {6}{G}{U}, creating two token copies of Omnath and Mystic Sanctuary.
Put all but one of the newest Omnath tokens into your graveyard due to the legend rule.
Each Mystic Sanctuary token created triggers, each Omnath you controlled prior to step 2's second abilities trigger twice, and each of the created Omnath token's first abilities trigger once.
Resolve both Mystic Sanctuary abilities, putting Doppelgang and up to one other instant or sorcery from your graveyard onto the top of your library.
Resolve both Omnath tokens' first triggers, causing you to draw two cards, including Doppelgang.
Resolve the remaining Omnath triggers, causing you to gain 8 life, add {R}{R}{G}{G}{W}{W}{U}{U}, and perform other actions dependent on how many times the specific abilities have triggered that turn.
Repeat.

Near-infinite ETB

Near-infinite LTB

Near-infinite blue mana

Near-infinite copies of all permanents

Near-infinite damage

Near-infinite death triggers

Near-infinite landfall triggers

Near-infinite magecraft triggers

Near-infinite mana permanents you control can produce

Doppelgang

Activate Soratami Mirror-Mage by paying {3} and returning Gaea's Cradle and two other mana-producing lands from the battlefield to your hand, returning Omnath from the battlefield to your hand.
Cast Omnath by paying {W}{U}{R}{G}.
Omnath enters the battlefield, triggering itself, causing you to draw a card.
Activate Patron of the Moon by paying {1}, putting Gaea's Cradle and another mana-producing land from your hand onto the battlefield tapped.
When the lands enter the battlefield, Omnath triggers twice and Amulet of Vigor triggers twice.
Resolve both Omnath triggers, causing you to gain 4 life and add {W}{U}{R}{G}.
Resolve both Amulet of Vigor triggers, untapping the lands that entered the battlefield.
Activate Gaea's Cradle by tapping it, adding at least {G}{G}{G}.
Activate the additional land by tapping it, adding {1}.
Activate Patron of the Moon again by paying {1}, putting the third land from your hand onto the battlefield tapped.
When the land enters the battlefield, Omnath and Amulet of Vigor trigger.
Resolve Omnath's trigger, dealing 4 damage to each opponent and each planeswalker you don't control.
Resolve Amulet of Vigor's trigger, untapping that land.
Activate that land by tapping it, adding {1}.
Repeat.

Combos with "Omnath, Locus of Creation"