Combo-based deck that aims to take out its opponents by creating infinite loops bouncing Cauldron Familiar, creating unlimited mana and casting multiple Drown in Dreams to deck opponents, or clearing opponents' boards with Venser, Shaper Savant. If that doesn't work out, the deck can also grind out value and wear opponents down with recursion loops and a bunch of ETB effects. The card selection in this build is geared more towards redundancy of the core effects needed to combo off and foregoes a number of the fun cards that are often played with Yarok (sorry Agent of Treachery).
Yarok's ability to get multiple triggers from Palinchron, Peregrine Drake, and Cloud of Faeries helps fuel most of the combos and lines of play, with Panharmonicon acting as backup just in case opponents either steal or repeatedly remove Yarok and make it too expensive to cast.
This deck is resilient thanks to its redundancy of key card effects and card recursion, consistent thanks to its notable number of tutor effects, and has the ability to ramp out mana very quickly. It can very often threaten wins on turns 5 or 6 if it is left to do its thing uninterrupted. However, the deck is moderately dependent on its commander to function at its most efficient and gets hammered pretty hard by Torpor Orb effects. Various forms of graveyard removal can also hamper some of the deck's combo lines. There is a decent amount of removal in the deck to deal with cards that are interfering with its combos but you may still end up in some situations where you are stuck waiting for the removal you need for several turns.
Yarok Combos:
Yarok, the Desecrated/Panharmonicon + Palinchron + 7 lands (4 of which produce blue mana without hurting you) = Infinite mana.
Yarok, the Desecrated/Panharmonicon + Shrieking Drake + Cloud of Faeries/Peregrine Drake (AEthersnipe + Peregrine Drake also works) = infinite mana as long as you have enough lands that produce blue mana. If you have enough blue mana sources to rack up infinite blue mana then adding Cauldron Familiar to the loop kills your opponents.
Combos Without Yarok:
Deadeye Navigator + Peregrine Drake/Palinchron = Infinite mana. Add Cauldron Familiar or Eternal Witness/Timeless Witness/Greenwarden of Murasa + Stroke of Genius in hand to kill all opponents. Venser, Shaper Savant clears all opponents' boards.
Eternal Witness/Timeless Witness/Greenwarden of Murasa + Ghostly Flicker/Displace + Peregrine Drake/Palinchron = Infinite mana. You can add Cauldron Familiar or Venser, Shaper Savant to this loop as well.
Creatures with ETB effects can also be worked into these combo loops for repeatable triggers. Infinite ETB triggers that draw you cards are as good as winning since they will draw you into one of your win conditions. Adding Cauldron Familiar once you have unlimited blue mana will kill your opponents while using Venser, Shaper Savant can clear opponents' boards.
Lines of Play
With Yarok/Panharmonicon on the board an entwined Tooth and Nail can close out the game.
Option A) (Needs at least 5 lands in play) Grab Peregrine Drake/Palinchron + rune-scared demon. Untap your lands and search for Eternal Witness and Displace/Ghostly Flicker. Use the instant to flicker the Drake and Demon to rack up more mana and tutor up Cauldron Familiar and any other card that you may want. Cast the Witness to get back your instant spell and any other card that you want from your graveyard. Use the instant spell to keep flickering the Drake and Witness to get infinite mana, then cast the Familiar from hand and keep flickering it and the Witness to drain your opponent's life.
This line can win without Yarok on the board as long as you have at least five lands out. Since the Demon will only tutor one card at a time get Displace/Ghostly Flicker first, flicker it and the Drake (tap your untapped to lands in response to the Drakes trigger to add 2 mana to your mana pool) and tutor up the Witness. You should now have all the pieces and mana you need to combo for infinite mana, tutor up the Familiar, and win the game.
Option B) Grab Palinchron if you have 6+ lands (Peregrine Drake works too if you have a land with a Wild Growth type enchantment on it) and Eternal Witness/Timeless Witness/Greenwarden of Murasa. Double Palinchron triggers thanks to Yarok gives you access to at least 12 mana while the Witness gets back Tooth and Nail. Recast Tooth and Nail to grab Deadeye Navigator and Cauldron Familiar. Soulbond the Navigator with the Palinchron, produce a bunch of blue mana, and then reset the soulbond to the Familiar to kill all your opponents.
Other Notable Lines:
You can use Birthing Pod/Eldritch Evolution to sac Cloud of Faeries for Eternal Witness, which will then return the sacrificed creature to hand. The same can be done with Peregrine Drake and Greenwarden of Murasa. This is useful for setting up infinite mana combos that use Displace/Ghostly Flicker.
