This is the most recent version of my Korvold infinites brew.

Since the last version I've added better tutors in the form of Grim Tutor, Fauna Shaman and Diabolic Intent, better early ramp with the addition of Gilded Goose, Elvish Mystic and Dark Ritual, and better interaction and protection in the form of Inquisition of Kozilek, Thoughtseize, Kenrith's Transformation, Tamiyo's Safekeeping and Veil of Summer.

Black Market Connections was also thrown in due to how versatile the card is.

(There was also a minor improvement in the manabase, with Ziatora's Proving Grounds and Takenuma, Abandoned Mire, but improving that aspect by a lot is hard because using rare wildcards on lands feels very bad) 

I've also added the Chatterfang, Squirrel General + Pitiless Plunderer infinite, as both cards are amazing in the build individually and, of course, game-winning when combined.

The objective of the deck stays the same, which is either win in the short term by smacking the opponent in the face with an early Korvold (now protected better than ever!), or assemble an infinite combo on the field and seal the game.

Infinites:

Putrid Goblin + The Great Henge/Grumgully, the Generous/Rhythm of the Wild + Skirk Prospector/Sling-Gang Liutenant/Woe Strider

This combo revolves around sacrificing infinitely Putrid Goblin with a +1/+1 counter dispenser on the field. It will always result in infinite ETB triggers and infinite sacrifice triggers, and may result in infinite damage (with Sling-Gang Liutenant or Mayhem Devil on board), infinite card draw (with The Great Henge or Korvold on board), infinite power on Korvold, infinite red mana (with Skirk Prospector) that can be sunk into an uncounterable Banefire, or even infinite life if you can't find a way to outright close the game (with Prosperous Innkeeper).

Chatterfang, Squirrel General + Pitiless Plunderer

This combo requires only 2 cards, but there is a lot less redundancy in the pieces, and requires a bit more setup than the ones above. To go truly infinite you need 2 squirrel tokens and open black mana, which means triggering Chatterfang twice before starting the combo. This will always result in infinite colored mana and infinite sacrifice triggers, which means always being able to put Korvold on board and draw the deck to find a way to close the game. The combo works even with one squirrel token, but it won't net infinite mana and will only result in wiping your opponent's board and infinite sacrifice triggers.

(You can go infinite with 2 squirrels even if your opponent has an empty board, just target your second squirrel with Chatterfang's ability with X=1)

UPDATE:

Switched out Claim the Firstborn, Springbloom Druid and Coldsteel Heart for Mishra's Bauble, Ashnod's Altar and surprisingly Stimulus Package, which has surprising utility and can go infinite with Pitiless Plunderer and a sac outlet!

Cards that feel the worst to play in the deck:

Grumgully, the Generous: This dude is here cause its a piece of the combo tutorable with Goblin Matron, which can come in handy at times, but compared to the other +1/+1 counter outlets it definitely does the least. The Great Henge being often free and offering card draw that can go infinite + some life gain, and Rhythm of the Wild being able to also give haste and protection from counterspells.

Binding the Old Gods: At 4 mana this card sits at the highest CMC of the deck (excluding The Great Henge), and it being only a removal spell with a bit of ramp attached to it feels a bit slow when compared to the rest of the deck. 

Destiny Spinner: This card is just here for the counterspell protection, so if the opponent is not into blue this card is pretty much useless.

Potential cards to add:

Altar of Dementia: Same as above but even more infinite centric, it's a sac outlet and payoff by itself, but outside of that it doesn't have a lot of applications.

Conclusion:

My objective is creating the best possible infinite Korvold list, so if anyone has any suggestion, please share!