Oko, Master Barterer Deck
Normally I would put this under Oko's Planeswalker Discussion page... (*coughcough* @Brigby *coughcough*) until then however, this will have to do.
Ever wanted to have the ability to play with your opponent's deck for the most part? Well, Oko is really good at doing just that. Now if only there was a way to constantly have the resources to make that work... oh wait... we have a certain someone that can make that a reality!
Fblthp, the Lost (R)
Once Upon a Time (R)
Casualties of War (R)
Golden Egg (U)
Simic Locket (U)
Temple of Mystery (U) / Land support of choice
Mirrodin Besieged (MP) / Artifact support of choice
Vanguard Supports (1):
Karn, the Great Creator (M)
This deck is designed to really go nuts with your opponent's deck (and strategy) once Oko's third ability gets out on the field. The fact that the High Fae Market is classified as only a "support" means it is that much harder to get rid of as a large number of support removal spells that aren't The Great Aurora or similar spells will have great difficulty removing it! So all we need then is the "resources" to trade to Greg...
Which is where everyone's favorite homunculus comes into play! Fblthp's ability to be fetched instead of everything else actually comes into its own in this deck. You'll always have a way to get Fblthp into your hand, waiting for the right moment to "trade" him for something of Greg's (which will always favor you because of the Fae Market!!).
Which is where the spells come in; either finding the homunculus from your deck, or controlling the battlefield. Once Upon a Time and Deathsprout both fetch Fblthp because they will try to find the land support in your library (but Fblthp will be fetched instead). Casualties of War is just a great meta card because of how many things it can potentally get rid of: vanguards, obnoxious enchantment supports hiding behind tokens, Gaea's Revenge shenanigans (when you can't just trade for it), among other things. Reclaim is for those times where you need to ramp a little faster and have an extra copy of Fblthp in your hand.
Support wise, the deck needs at least one land for Deathsprout to fetch Fblthp, so use whatever works for you. Golden Egg is cheap, works with Oko's first ability, and is always useful for trading. Simic Locket is also a great barter tool once the market is in play, otherwise it can help with gem conversion. If you have it, Mirrodin Besieged can also help by producing Myr tokens...
Which Karn, the Great Creator can disable if they get traded to Greg! Karn also keeps Greg from playing artifact supports - which allows the Fae Market to trade to you for your artifact supports you don't need and want to clutter Greg's hand with! Don't have Mirrodin Besieged? Then use another artifact support of your preference to round out the deck.
DISCLAIMER: In testing, this deck is causing a number of "weird" abnormalities - mostly lag related in relation to the High Fae Market after attacks... But I've also been traded artifact supports that stay disabled from Karn's passive... So be ready for who knows what might happen...