Mist Valley 1-Card Negate

This deck uses a single card (anything that can summon Crystron Halqifibrax, except Jet Synchron) and a card to discard to set up the Mist Valley infinite negate (Apex Avian + Thunderbird) on the first turn.

The combo:

-Special Summon Crystron Halqifibrax (There are many ways to do this). Use its effect to Summon Mecha Phantom Beast O-Lion.

-Summon Linkross with Halqifibrax, summoning 2 Link Tokens

-Use O-Lion and 1 of the Tokens to Summon Martial Metal Marcher. Use O-Lion's effect to Summon a Mecha Phantom Beast Token, and use Marcher's effect to revive O-Lion.

-Use O-Lion and the Mecha Phantom Beast Token to summon Accel Synchron. Use Accel Synchron's effect to send Jet Synchron to the GY and increase or decrease its level by 1.

-Discard 1 card to summon Jet Synchron from the GY, then link into Linkuriboh.

-Use Linkuriboh and Marcher to Summon Reprodocus. Use its effect to make Linkross a Winged Beast.

-Link Summon Simorgh, Bird of Sovereignty with Reprodocus and Linkross

-Tribute the other Link Token to summon Linkuriboh, then use it and Accel Synchron to summon Union Carrier.

-Use Union Carrier's effect to equip Mist Valley Thunderbird to Simorgh.

-Set or activate a card to protect Mist Valley Thunderbird from destruction in battle, if you have one.

-End your turn, and use Simorgh's effect to Summon Mist Valley Apex Avian.

At this point, you will be able to negate anything once per chain, and if you have Raregold Armor or a similar card your Mist Valley Thunderbird will be protected from attacks.

Full Deck Breakdown:

Deep Sea Diva x3, Tour Guide from the Underworld x2, Sangan x3, Righty Driver x3, Draconnet x3: Used to summon Halqifibrax, start the combo.

Crusadia Arboria x1, Lefty Driver x1, Guardragon Justicia x1: Needed for Snagan, Righty Driver, Draconnet

Mecha Phantom Beast O-Lion x1, Jet Synchron x2, Mist Valley Thunderbird x1, Mist Valley Apex Avian x1: Needed for combo, Jet Synchron is at 2 because otherwise drawing it would destroy the combo.

Raregold Armor x3, Armory Call x3, Vengeful Bog Spirit x3, Red Screen x3, Stumbling x3, Wall of Revealing Light x1: These cards are extremely helpful in protecting Mist Valley Thunderbird after it has been Summoned to the field.

Prohibition x3: Useful for preventing Ash Blossom or Nibiru from wrecking the strategy.

Called by the Grave x3: Used to counter Ash Blossom and Effect Veiler.

Extra Deck:

Akashic Magician, Salamangreat Almiraj x1: Used with Sangan or Tour Guide to enable link summons with Arboria.

Crystron Halqifibrax x2, Linkross x2, Martial Metal Marcher x2, Accel Synchron x1, Linkuriboh x1: These cards are needed for the combo. Halqifibrax, Linkross, and Marcher are at 2 so you can restart the combo if you run into Ash Blossom or Nibiru. The extras can be replaced if necessary.

I:P Masquerena x1, Mekk-Knight Crusadia Avramax x1: These cards are good to have for later game (turns 2+) summons. Avramax in particular is good for locking down attacks.

Side deck:

Nibiru the Primal Being x3: Good for stopping opposing combos, if forced to go second.

Dark Ruler No More: This is one of the best cards for negating opponent's cards that would threaten the combo.

Lightning Storm x3: To break boards with troublesome cards and/or bait cards like Savage Dragon or Dragoon.

Infinite Impermanence x3: To negate opponent's monsters or bait their negation effects. Also good to stop Spells/Traps.

Ash Blossom & Joyous Spring x3: Good for stopping combo decks before they start.