The main "combo" is between Cauldron Familiar and Witch's Oven. Tap the Oven to sacrifice the Cat and create a Food Token, then sac the Food to return Cauldron Familiar to the battlefield, draining your opponent for 1.
The deck is pretty self explanatory. Usually, Cat Food in Standard operates like an aristocrat deck banking on the fact that you're getting a creature and an artifact into play each turn and having a creature and an artifact die each turn. The deck above though only really takes advantage of that by running Trail of Crumbs to bury the opponent in card advantage. The cards that I find suspect are the Glint-Nest Crane, which is their to search for the Oven, and Strategic Planning, which is also their for card selection. Massacre Girl is an intresting board wipe that takes advantage of the dying cats, but i'm wondering if that is putting all the eggs into one basket? I am not sure if I have any huge idea on how to improve the deck except maybe move Thoughtseize somehow into the mainboard, but the deck looks intresting as a grindy type deck. It's 5-0 finish shows that it's theoretically playable in pionneer, it just needs to be worked a bit.
The 5-0 finish probably has more to do with Oko than anything else to be honest as this deck looks all over the place and not particularly focused.
The cat-oven interaction doen't seem strong enough to build around and Trail of Crumbs doesn't seem that great compared to other card advantage engines you can use like Evolutionary Leap (or Tireless Tracker).
The deck also has no interactive spells (besides Oko) in the maindeck which seems bizzare for a deck with such a slow clock.
I saw Evaros stream a similar build last night, with Korvold, Fae-Cursed King as the payoff. I only caught the first match where he dunked on a simic stompy deck, but Korvold really brought the deck together. If you can't find the list on Evaros' streamdecker give me a shout and I'll find a timestamp for the Vod
Another thought I had was that the combo get's better with untap effects. The other card that gets better with untap effects in Pioneer is Lotus Field. Now there won't be enough cards to stuff Cat Combo into Hidden Strings Combo, but there could be a hybrid that can make room for Big threats powered out by Lotus Field and constant drain from Cat Combo.
don't have time to find Evaros' list tonight, sry, will grab it soon. Someone also streamed a Jund list running Mayhem Devil and God-Eternal Bontu that had the advantage of boshing out 15 damage turns in the lategame if the board stalled
This interaction made some headway in Standard, and I am curious if it can make the jump to pioneer. Someone actually piloted a version of the deck into a Pioneer 5-0 finish, so I will work off their list.
4 Cauldron Familiar
4 Gilded Goose
4 Glint-Nest Crane
2 Hangarback Walker
3 Massacre Girl
2 Strategic Planning
4 Once Upon a Time
4 Smuggler's Copter
4 Witch's Oven
4 Trail of Crumbs
4 Botanical Sanctum
2 Forest
1 Island
4 Overgrown Tomb
2 Swamp
4 Watery Grave
4 Battle at the Bridge
4 Rotting Regisaur
3 Thoughtseize
3 Vraska, Golgari Queen
The deck is pretty self explanatory. Usually, Cat Food in Standard operates like an aristocrat deck banking on the fact that you're getting a creature and an artifact into play each turn and having a creature and an artifact die each turn. The deck above though only really takes advantage of that by running Trail of Crumbs to bury the opponent in card advantage. The cards that I find suspect are the Glint-Nest Crane, which is their to search for the Oven, and Strategic Planning, which is also their for card selection. Massacre Girl is an intresting board wipe that takes advantage of the dying cats, but i'm wondering if that is putting all the eggs into one basket? I am not sure if I have any huge idea on how to improve the deck except maybe move Thoughtseize somehow into the mainboard, but the deck looks intresting as a grindy type deck. It's 5-0 finish shows that it's theoretically playable in pionneer, it just needs to be worked a bit.
The cat-oven interaction doen't seem strong enough to build around and Trail of Crumbs doesn't seem that great compared to other card advantage engines you can use like Evolutionary Leap (or Tireless Tracker).
The deck also has no interactive spells (besides Oko) in the maindeck which seems bizzare for a deck with such a slow clock.
EDIT:
Another thought I had was that the combo get's better with untap effects. The other card that gets better with untap effects in Pioneer is Lotus Field. Now there won't be enough cards to stuff Cat Combo into Hidden Strings Combo, but there could be a hybrid that can make room for Big threats powered out by Lotus Field and constant drain from Cat Combo.
Edit: I like the untaping idea personally just because the drain can help save you from aggro. A quick list I put together to test out:
4 Kiora, Behemoth Beckoner
4 Cauldron Familiar
4 Gilded Goose
3 Vizier of Tumbling Sands
4 Ulamog, the Ceaseless Hunger
4 ThoughtSeize
3 Hidden Strings
4 Once Upon a Time
18 Lands
The idea here is either slowly drain with Cat Food Combo plus untapping effects, or land a Lotus Field, and untap it twice and cast Ulamog.
4 Cauldron Familiar
4 Gilded Goose
3 Reassembling Skeleton
4 Mayhem Devil
4 Midnight Reaper
2 Korvold, Fae-Cursed King
2 Vraska, Golgari Queen
4 Fatal Push
4 Thoughtseize
4 Witch's Oven
1 Blooming Marsh
1 Castle Locthwain
1 Dragonskull Summit
3 Fabled Passage
1 Field of the Dead
2 Forest
1 Mountain
4 Overgrown Tomb
1 Stomping Ground
2 Swamp
1 Urborg, Tomb of Yawgmoth
3 Woodland Cemetery
4 Assassin's Trophy
2 Scavenging Ooze
2 Sorcerous Spyglass
3 Kolaghan's Command
2 Liliana, the Last Hope
75 Cards Total
It looks very robust!
4 Elder Deep-Fiend
4 Emry, Lurker of the Loch
4 Haunted Dead
4 Prized Amalgam
4 Scrapheap Scrounger
4 Stitcher's Supplier
2 Thoughtseize
4 Smuggler's Copter
4 Witch's Oven
4 Choked Estuary
4 Drowned Catacomb
2 Island
5 Swamp
1 Urborg, Tomb of Yawgmoth
4 Watery Grave
This uses Emry to bury and then get out the oven and has a lot more graveyard shenanigans.
This list post Copter ban was theorized as:
3 Haunted Dead
4 Scrapheap Scrounger
4 Cauldron Familiar
4 Emry, Lurker of the Loch
4 Prized Amalgam
4 Satyr Wayfinder
4 Stitcher's Supplier
4 Oko, Thief of Crowns
4 Grisly Salvage
4 Witch's Oven
Lands
1 Ipnu Rivulet
1 Mana Confluence
1 Urborg, Tomb of Yawgmoth
4 Blooming Marsh
4 Botanical Sanctum
4 Overgrown Tomb
4 Watery Grave
2 Thoughtseize
2 Pithing Needle
1 Tormod's Crypt
2 Assassin's Trophy
2 Abrupt Decay
2 Scavenging Ooze