World-Eater
Why Sacrifice your creatures when you can merely consume the ground on which they walk?
The purpose of the deck is to ramp quickly, playing multiple lands a turn, so that you can sacrifice them to bring back later. You can sacrifice creatures if necessary, but lands are going to be your main source of fodder for your commander Korvold, Fae-Cursed King.
Rocky Road
Here we find our basic Mana-rocks. Sol Ring and Arcane Signet are always staples, and also we have Commander's Sphere, which can also be sacrificed to our commander. Likewise, Golden Egg also can be sacrificed to Korvold, while acting as a Mana-filter, or a bit of life-gain, while also giving a bit of card advantage upon playing it. We don't have much in the way of mana-rocks, since most of our deck revolves around lands.
This Land is MY Land
Exploration starts us off, allowing us to play an additional land every turn. Ghirapur Orrery gives us another additional land -- though at the expense of our opponents also getting to do so -- and Mina and Denn, Wildborn does the same, but in creature form.
Both Walking Atlas and Llanowar Scout are creatures for two mana that can each tap to allow yet another additional land, but are limited to merely putting them into play from your hand at that moment. Krosan Wayfarer can do the same when it is sacrificed. The two sorcery cards Explore and Broken Bond allow you to draw and Destroy an Artifact/Enchantment, respectively, while also getting even more land.
Cards like Courser of Kruphix, Druidic Satchel, The Mending of Dominaria, Ramunap Excavator, and Splendid Reclamation give you the ability to put lands into play from the top of your library or from your graveyard. Meanwhile, Groundskeeper, Gaea's Blessing, Life from the Loam, and Nature's Spiral allow you to bring lands back from your Grave and put them into your hand or library.
Lord Windgrace works as a draw engine, as well as bringing lands back to the battlefield. For the most part, we're going to ignore that last ability.
Takes Two to Tutor
In the Land category, we have Terramorphic Expanse, Evolving Wilds, and Jund Panorama can each tutor for a basic land. Played early game, they can be used to fix your mana, and late game, can be easy sacrifices for Korvold.
Similarly, the creatures Sakura-Tribe Elder and Burnished Hart can be sacrificed to search out some basic land, and Fertilid can't sacrifice to tutor, but can get two basic lands.
Primal Growth and Harrow both basically do the same thing, if Primal Growth is kicked by sacrificing a creature. Both utilize a sacrifice, and both can get you two basic lands. Deathsprout allows you to kill a creature and search for a land, and Rampant Growth doesn't even need an explanation.
Hit the Sack
Starting Simple, we have Blood Pet, which can sacrifice itself to generate one black mana.
While Land sacrifice is the main focus of this deck, the creatures themselves are no slouches. Keldon Champion, Keldon Marauders, Spark Elemental, Hellspark Elemental, Skizzik, and Ball Lightning are all creatures that are stuck with limited time before they must be sacrificed to their own effects. Priest of the forgotten gods, Disciple of Griselbrand, and Bloodthrone Vampire all have effects that work by sacrificing creatures you control, while Fleshbag Marauder forces everyone to sacrifice a creature when it comes into play, and Plaguecrafter does the same, but also includes Planeswalkers. And Angrath's Rampage is a sorcery that makes a player sacrifice either an Artifact, a Creature, or a Planeswalker.
And then we come to perhaps the most useful card in the deck, Sylvan Safekeeper. Sacrificing lands AND Protecting your creatures all in one.
Your Pain Amuses Me
We'll start here with the enchantment Moldervine Reclamation, where when the creatures above die, we're gonna gain a life and draw. Falconrath Noble drains target player for one any time it or another creature dies. Vindictive Vampire does similar, in that whenever another creature we control dies, it pings each opponent for one while gaining us one life in return.
Mayhem Devil pings any target for one when anyone sacrifices a permanent, and Mazirek, Kraul Death Priest has flying and puts a +1/+1 counter on every creature we control whenever anyone sacrifices another permanent.
A Token of my Appreciation
As this category would suggest, these cards each spawn tokens, which can be used variously for sacrificing to Korvold, Sacrificing to other creatures, or gaining life.
Gluttonous Troll, Savvy Hunter, Taste of Death, Bake into a Pie, and Witch's Oven each generates Food Tokens, while feeding your sacrificing in the process. Rapacious Dragon is a flier that spawns two Treasure Tokens upon entering the battlefield. Orzhov Enforcer has deathtouch and produces a 1/1 flier upon death, and Chittering Witch creates Rat tokens which can be sacrificed to weaken opponents' creatures.
Rite of the Raging Storm gives each player a 5/1 Elemental with Haste during their turn that must be sacrificed at the end of that turn. This token cannot attack us, meaning your opponents are smacking each other while you get a stable sacrifice every turn for Korvold. Mask of Immolation is an equipment that when it enters the battlefield creates a 1/1 Elemental and equips to it. Any creature equipped with the Mask can sacrifice itself to ping any target for one.
Land-Lord
First up we have Zendikar's Roil, Sporemound, and Rampaging Baloth, which create a 2/2 Elemental, a 1/1 Insect, and a 4/4 Beast respectively whenever a land enters the battlefield under our control. Given how many lands we can put out a turn once this deck gets going, these tokens are gonna turn into an Army very quickly. Similarly, Omnath, Locus of Rage produces a 5/5 Elemental for its landfall trigger, while making our other Elementals into lightning-bolts whenever they die.
Then we've got Titania, Protector or Argoth. Upon entering the Battlefield, we can put a land from our grave into play. However, it's her second ability that really works with Korvold, and Sylvan Safekeeper as well. Any time one of our lands is put into the grave from the battlefield, we get a 5/3 Elemental.