Pay {0} to activate Outrider en-Kor, targeting Task Force.
Task Force triggers, giving itself +0/+3 untill end of turn.
Repeat steps 1-2 untill Task Force has infinite toughness.
Tap Diamond Valley sacrificing Task Force, gaining life equal to its toughness.

Infinite lifegain

Outrider en-Kor

Task Force

Diamond Valley

Activate Diamond Valley by tapping it and sacrificing Serra Avatar, causing you to gain life equal to Serra Avatar's power.
Sanguine Bond triggers, causing target opponent whose lifetotal is less than or equal to Serra Avatar's power to lose life equal to the life you gained.
The opponent loses the game due to having zero or less life.

Near-infinite lifegain

Near-infinite lifeloss for target opponent

Target opponent loses the game

Serra Avatar

Sanguine Bond

Activate Diamond Valley by tapping it and sacrificing Serra Avatar, causing you to gain life equal to Serra Avatar's power.
Vito triggers, causing target opponent whose lifetotal is less than or equal to Serra Avatar's power to lose life equal to the life you gained.
The opponent loses the game due to having zero or less life.

Vito, Thorn of the Dusk Rose

Activate Vizkopa Guildmage's second ability by paying {1}{W}{B}, causing each opponent to lose life when you gain life this turn.
Activate Diamond Valley by tapping it and sacrificing Serra Avatar, causing you to gain life equal to Serra Avatar's power.
Vizkopa Guildmage triggers, causing each opponent to lose life equal to the life you gained.
Each opponent loses the game due to having zero or less life.

Each opponent loses the game

Near-infinite lifeloss

Vizkopa Guildmage

Activate Diamond Valley by tapping it and sacrificing Soul of Eternity, causing you to gain life equal to Soul of Eternity's power.
Sanguine Bond triggers, causing target opponent whose lifetotal is less than or equal to Soul of Eternity's power to lose life equal to the life you gained.
The opponent loses the game due to having zero or less life.

Soul of Eternity

Activate Vizkopa Guildmage's second ability by paying {1}{W}{B}, causing each opponent to lose life when you gain life this turn.
Activate Diamond Valley by tapping it and sacrificing Soul of Eternity, causing you to gain life equal to Soul of Eternity's power.
Vizkopa Guildmage triggers, causing each opponent to lose life equal to the life you gained.
Each opponent loses the game due to having zero or less life.

Activate Diamond Valley by tapping it and sacrificing Soul of Eternity, causing you to gain life equal to Soul of Eternity's power.
Vito triggers, causing target opponent whose lifetotal is less than or equal to Soul of Eternity's power to lose life equal to the life you gained.
The opponent loses the game due to having zero or less life.

Activate Diamond Valley by tapping it and sacrificing Palinchron, gaining you 5 life.
Activate Atzal's second ability by paying {3}{B}{G} and tapping it, returning Palinchron to the battlefield.
Palinchron enters the battlefield, untapping Atzal, Diamond Valley, and five other lands that can produce {3}{B}{G}.
Repeat.

Infinite colored mana

Infinite death triggers

Infinite ETB

Infinite lifegain triggers

Infinite LTB

Palinchron

Journey to Eternity // Atzal, Cave of Eternity

Activate Diamond Valley by tapping it and sacrificing Palinchron, gaining life equal to Palinchron's toughness.
Nim Deathmantle triggers, costing you {4} to return Palinchron to the battlefield, and attach Nim Deathmantle to Palinchron.
Palinchron enters the battlefield, untapping Diamond Valley and up to six lands you control that can produce at least {5}.
Activate up to six lands by tapping them, adding at least {5}.
Repeat.

Infinite mana lands you control can produce

Infinite sacrifice triggers

Nim Deathmantle

Activate any number of lands except Urza's Saga by tapping them, adding at least {2}.
Activate Urza's Saga's second ability by paying {2} and tapping it, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control, and that enters the battlefield with a number of +1/+1 counters equal to Arwen's toughness.
Activate the Construct using Beledros Witherbloom's ability by paying 10 life, untapping all lands you control.
Activate Diamond Valley by tapping it and sacrificing the Construct, causing you to gain at least 10 life.
Repeat.
If the number of artifacts you control plus Arwen's toughness is equal to or greater than 10, this combo nets infinite life, and if other lands you control can tap to produce at least {3}, this combo nets infinite mana.
If you get infinite life and infinite mana, you may forego sacrificing the Constructs.

Infinite creature tokens

Infinitely large Construct tokens

Infinite untap of lands you control

Beledros Witherbloom

Urza's Saga

Agatha's Soul Cauldron

Arwen, Weaver of Hope

Activate Diamond Valley by tapping it and sacrificing Great Whale, gaining you 5 life.
Activate Atzal's second ability by paying {3}{B}{G} and tapping it, returning Great Whale to the battlefield.
Great Whale enters the battlefield, untapping Atzal, Diamond Valley, and five other lands that can produce {3}{B}{G}.
Repeat.

Combos with "Diamond Valley"