Looks pretty cool. I like the idea of building around Spy Kit, especially as part of a big engine.

Just off the top of my head: why not Noxious Revival in place of Reclaim? Might be nice to play it mana-free once in a while, plus you can also use it to sabotage an opponent's reanimation spell. You might also appreciate Selesnya Signet over, say, Search for Tomorrow, which always seemed like an underwhelming card to me.

ClockworkSwordfish

Noxious Revival: Hard to argue with "strictly better"-- that's going right in. Thanks!

And I really love Search for Tomorrow. This deck wants to ramp repeatedly early on, and Search lets me do that on turn 1, without being dead later. I also like the land coming in untapped. Signet's the current runner-up on ramp. If I find an underperformer, it goes in.

Weirdly, I want to ramp enough that I often find myself doing a turn 3 Reclaim to get my 1-use ramp back and do it again.

ClockworkSwordfish

Noxious Revival: Hard to argue with "strictly better"-- that's going right in. Thanks!

And I really love Search for Tomorrow. This deck wants to ramp repeatedly early on, and Search lets me do that on turn 1, without being dead later. I also like the land coming in untapped. Signet's the current runner-up on ramp. If I find an underperformer, it goes in.

Weirdly, I want to ramp enough that I often find myself doing a turn 3 Reclaim to get my 1-use ramp back and do it again.

I'm absolutely blown away. Stuff like this is the reason why I love this game. I've been struggling to put together my Nazahn deck (got the precon for my birthday and liked the look of him the most) and came across this just searching around. Easily one of the most interesting EDH decks I've ever seen, I fully plan on putting together my own version of this combo. Well done on this!

Have you tried using Mortarpod? It seems to work better than Demonmail Hauberk while it's not a free sac outlet, but with ashnod's altar + wurm it wins the game on the spot since you can loop doing 1 damage to everyone.

So, from my testing, this deck really needs a Riftsweeper. Lets you get back exiled spy kit or any other combo pieces, and lets you reuse Academy Rector. I think Eidolon of Blossoms could probably be cut, given that it rarely seems to do a whole lot in my experience

I tutor for Eidolon once in a while-- it's a green creature that I can loop, it draws cards if that's what I need, and I can grab it with basically any tutor I want.

Damn I'd love to have a slot for Riftsweeper, though. Sun Titan ain't so great, right? :P

Playtesting note: A lot of my combo turns start with "I equip Conqueror's Flail. Any responses?"

Love the deck. Have you considered the classic Verdant Succession partner that is Wheel of Sun and Moon?

Whym_: That actually doesn't work-- Wheel of Sun and Moon is a replacement effect, so Verdant Succession never triggers.

Loaming Shaman acts a bit like Worldspine Wurm and Arashin Sovereign, if you sac him with the ETB trigger on the stack you can shuffle him back in like he has a built in Soldevi Digger. Plus it has applications in other scenarios.

Streakist: That's quite good! Drivin' those combo pieces down in CMC, slowly.

If there is room for it Grand Abolisher could be used as combo protection redundancy.

Planned changes: Sungrass Prairie out, Dryad Arbor in. Remembrance out, Green Sun's Zenith in.

Prairie forced a mulligan on a hand where I needed an unconditional land, so screw it. Remembrance is cute but who wants to pay casting costs?

Meanwhile, GSZ + Dryad Arbor is a slam dunk. Not only do they work together as turn 1 ramp, GSZ fetches any number of combo pieces, and Dryad Arbor is a green creature that I can play without casting.

what about Sigarda's Aid? that free flash attach to a creature skips the equip cost, and then you can flash equip the next creature you tutor up. Puresteel Paladin would allow you to do it for free too

Also on the chopping block: a Plains and Lurking Predators for Riftsweeper and Loaming Shaman.

More cuts to find? I want more spot removal, or maybe another wipe.

No room for blue, unfortunately... As a suggestion, with the amount of recursion you have, Novablast Wurm might be an interesting choice if you're looking for a wipe. On a smaller but more spot removal-y scale, Bramblecrush is a pretty versatile option. Honestly, all of the cards I was going to suggest are already in here. Great idea, solid execution.

This is amazing. Do you plan to keep it updated? Is there room for God-Eternal Rhonas in here?

XaiLo: Yes, I plan to keep this list up-to-date. On that note, God-Eternal Rhonas seems like a slam dunk, and I should probably replace Elvish Soultiller with it. Thanks!

Does Blade of Selves have any use here? It's my favorite card, and it does nice things with Nazahn in a regular Nazahn deck. But I'm wondering if it could fit into Spy Cat as well?

I noticed you don't run Savannah. Is that a budget call or a strategic one? Also not running Survival of the Fittest. Is that because of budget?

How is your early ramp? Most competitive decks run things like Wild Growth, Utopia Sprawl, Carpet of Flowers, other 1 cmc dorks etc, rather than Skyshround Claim, Cultivate, etc. (Three Visits is another nonbudget card that I think is better than Cultivate in a competitive combo deck. There's also Arcane Signet, Talisman of Unity, Fellwar Stone, Mana Crypt, etc)

Would it be possible to shave off some combo lines, focus on only the best ones, and free up more slots for ramp and maybe removal/interaction like Nature's Claim or Veil of Summer or Rebuff the Wicked.

I totally get why this deck doesnt run hate bears like most competitive GW decks would. But on the other hand, I worry about it not having enough removal for OPPONENTS' hate pieces which could stifle the combo.

XaiLo: Savannah is a pure budget decision-- I simply haven't got one. Survival of the Fittest, though, I just had my one copy in another deck, but that deck isn't presently together. I'm going to be fitting that in as soon as I can. Good call.

As far as tuning the deck more, reducing the ramp curve and adding cheaper interaction, I dunno. I want to make sure I can play it at a regular table without running everyone over. If I find the right meta, I might find room for Mana Crypt and Mana Vault.

Cut Skyshroud Claim for Survival of the Fittest since you don't need ramp if you can tutor up your ramp creatures and also anything else -- thanks XaiLo

Cut Epitaph Golem for Reveillark, since that's the literal worst combo piece in the deck and Reveillark fishes most of the winners out of my yard. -- thanks Black_Eagle of ##mtg

Easy swap: Sythis, Harvest's Hand for Eidolon of Blossoms. It doesn't draw on ETB, but otherwise fills the niche of "green creature that is also an enchantment" just as well for the tutors.

Mana Vault in for a Forest, bringing land count down to 35.