What makes a good cube? There are as many opinions on this as there are cubes out there. This cube tries to incorporate a couple of these into one whole experience. The most important ones are the following:

Archetypes that dictate the strongest strategy available.
This statement alone has a few ideas that need to follow it in order to be true. Namely, that card's shouldn't be individually strong enough to win you the game, but that the stronger cards of the environment should require synergy to reach their full potential. Furthermore, the archetypes need to be consistent enough to come together in a draft, meaning that adequate support for the defining archetypes is required.

Archetypes that share cards between them.
With Synergy as a forefront to a cube, there is the pitfall of what some call a "draft-on-rails": Once you have decided on the archetype you want to play during draft, all future picks become very simple, as cards only go into one specific archetype. This can be mitigated by cards that serve function in multiple archetypes, which in turn requires archetypes that share some things they want to do. Forexample, if we look at Quasiduplicate, there are multiple archetypes that would be delighted to pick this card. Spellslinger decks would be thrilled to cast a Sorcery that triggers their Talrand, Sky Summoner while at the same time creating a creature. On the other hand, a Discard-deck could use it's Jump-Start ability to create a token with Drake Haven, or maybe a reanimator deck wants to get Omnath, Locus of Rage into the graveyard.

Interactive Gameplay.
Now, when hearing "interactive", your first thought might be "removal". While removal certainly has its place, as it balances cards that might be to strong if left unchecked, if that were the only thing interactive in a cube, games would still come down to "who can create the best boardstate wins". This is where in regular limited formats combat tricks would come in, introducing a certain degree of uncertainty (hehe). However, only a select few are strong enough for cube, and so another path a cube might go down is the keyword Morph. Now, this mechanic has never been printed to such an extent that it would warrant creating its own archetype. Therefore only 10 creatures with this mechanic are included here, but that already helps bring a bit of uncertainty to the table. Another way we can involve both players at the same time, are cards like Fact or Fiction and Risk Factor. Even if you aren't the one playing the card, you can still easily influence how strong these cards will affect the outcome of the game, by making smart decisions. Lastly, having more options in general is a great way of making games interactive, as it allows you to react differently depending on what your opponent is doing. Good examples for this are Charming Prince, Fire // Ice and Umezawa's Charm.

High competition for cards during draft.
The goal of this one is to make the draft challenging: You will never be quite sure whether that second card you want from a pack is going to come back to you or not. The decisions which achieve this goal are the following: Having an even power level among all the cards. Now, this can never be achieved in it's entirety, but it is necessary to strife towards it. Secondly, prioritising Colorless and Hybrid cards over Gold cards. Since gold cards can only be picked up by players in specific color combinations, they tend to wheel, which goes against this philosophy. Colorless and Hybrid cards on the other hand can be used in basically any deck, and so are easier to include.

Together, these principles result in a rich and satisfying draft and gameplay experience. If you feel up for it, why not give it a try and do a test draft? I'd be thrilled to see what you can come up with.

Detailed look at/guide for the Archetypes:

Grixis Madness/Discard:

Key Payoffs: Drake Haven, Circular Logic, From under the Floorboards, Reckless Wurm

Shares cards with: Reanimator, Graveyard, Spellslinger

With this deck, you are looking to make good use of discard outlets like Merfolk Looter in order to enable your madness payoffs. Therefore, a good balance between discard outlets and Payoffs is required, which can sometimes be tricky to get right. Repeatable, low cost outlets like Olivia's Dragoon or Dismissive Pyromancer are your favorite discard outlets. The low cost ensure you will be able to pay the required madness cost. And repeatable means you will be able to discard multiple madness cards over following turns with just one outlet.
Because you need a bit of setup in order to madness, and your incentivized to go for all 3 Grixis colors, this deck often takes on a more controlling form. This also allows you to make use of other incidental synergies, like reanimator or Spellslinger, which often mesh nicely with your discard outlets and high instant/sorcery density. However, a more aggresive variant with cards like Bloodrage Brawler or Furyblade Vampire is not unthinkable.

Dimir Reanimator:

Key Cards: Magmatic Force, Omnath, Locus of Rage, Dread Return, Ever After

Shares cards with: Madness, Graveyard

Often more of a subtheme for a deck, rather than a go-to archetype. At the time of this writing, 6 reanimation spells are in the cube, plus an about equal number of big creatures to reanimate. Therefore, decks will often start out in either the madness or graveyard archetype, and upon seeing either a big creature or a reanimation spell will adjust to seek out the other. Due to the setup required, this also is a more controlling archetype, usually able to oulast the opponent upon reaching the later stages of gameplay. However, getting there can be tricky, so sweepers and good removal/blockers should be prioritized.

Izzet Spellslinger:

Key Payoffs: Rise from the Tides, Young Pyromancer, Talrand, Sky Summoner

Shares Cards with: Madness

Pretty self-explanatory, pack some good blue card draw, red removal and some of the above payoffs. Also don't forget to add some creatures, especially usefull are the ones that come in the form of sorceries like Talrand's Invocation or Hordeling Outburst. In case you do get Rise from the Tides, be on the lookout for cards that let you cast it a second time, like Archaeomancer or The Mirari Conjecture for overwhelming value. Maybe even Geistblast??

Golgari Graveyard

Key cards: Spider Spawning, Kessig Cagebreakers, Kindly Stranger, Bloodsoaked Champion

Shares cards with: Reanimator, Sacrifice

This deck archetype of utilising its graveyard as a resource. This is usually accomplished by 1. having cards that can be cast from the graveyard, or 2. reference the size of your graveyard for the size of their effect. Depending on the specific payoff you are building around for this deck, you have to prioritise different cards. All of these deck are interested in selfmill (Stitcher's Supplier), but decks running Spawning or Cagebreakers are also interested in a high creature count. That way, you can often play a midrange-style deck that finally has a big finisher to close games.
On the other hand, this is one of the very few archetypes that can run Emrakul, the Promised End. If you do want to cast her, not just reanimate her, then you will have to heavily build around her, by one making sure you have all card types in your deck. Secondly, you have to play a pretty controlling deck, since even with all 6 card types available in the grave, it still costs seven mana to cast. That makes Languish or Nevinyrral's Disk highly valuable to you. Lastly, some graveyard recursion helps in case you mill over Emrakul, see Den Protector or The Mending of Dominaria.

Non-Blue Sacrifice:

Key Payoffs: Blood Artist, Priest of Forgotten Gods, Smothering Abomination, Gutterbones

Shares Cards with: Token, Graveyard

This is a bit of a messy archetype, and is probably best avoided by the uninitiated. It can include all colors outside of blue, though Black is pretty much always included for its abundance of sack outlets, while green is often more of a splash color for good sacrifice fodder, see Awakening Zone. That means the most common two-color combinations are Orzhov and Rakdos. Common to all Sacrifice decks is their need for two things: Sacrifice outlets and good fodder. White does this effectively through an abundance of small creatures and tokens (Ministrant of Obligation, Promise of Bunrei), while red also has tokens, but additionally the ability to use enemy creatures as fodder through Act of Treason or Malevolent Whispers.

Next: Aggro, Auras, Tokens, Flicker, Lifegain, Temur Tempo/Midrange

Addlist:
White: Hanweir Militia Captain, Whitemane Lion, Sheperd of the Flock, Silverflame Squire, Ephemerate, Blessed Alliance?, Gallant Cavalry, Sentinel's Eyes, Sentinel's Mark, Master Trinketeer?, vesperlark (for combo) , cradle of vitality, Alseid of Life's Bounty

Blue: Hypnotic Sprite?, Chromeshell Crab?, Shu Yun, the Silent Tempest?, Thassa's Intervention?, Merfolk Trickster, Identity Thief, Nephalia Smuggler

Black: Silumgar Assassin, Skinthinner?, Gruesome Menagerie, Liliana, Heretical Healer??, Foreboding Fruit!, Ruthless Disposal, gravebreaker lamia?, vengeful Rebel?, LICHS MASTERY??, Boneyard Mycodrax, bloodbond vampire (owned?), tomb robber, bone miser, Warteye Witch

Red: Makeshift Munitions, Captivating Crew, Claim the Firstborn, Anje's Ravager, Storm Herald (Owned)?, Kazuul's Toll Collector, Akroan Line Breaker, Heroes of the Revel, Zada Hedron Grinder, Labyrinth Champion, Champion of the Flame!, Mogis's Warhound,
Rimrock Knight, Tuktuk the Explorer, Coordinated Assault, barrage of expendables, collateral damage, squee goblin nabob

Green: Moldervine Cloak, Fists of Ironwood, Karametra's Favor, Raised by Wolves, Treefolk Umbra, Golgari Raiders(for Boneyard
Wurm), Eidolon of Blossoms?, Band Together!, Gnarlback Rhino, Cultivator of Blades/Gobbling Ooze[[Pine Walker]], Voyaging Satyr,
Anthousa, Setessan Hero,
Gold: Cruel Celebrant, GR Savage Smash?/Rythm of the Wild, Anax and Cymede/Tenth District Legionaire, Siona, Captain of the Pyleas

Colorless: Sword of the Animist, Apostle's Blessing, Agent of Acquisitions, Cloudstone Curio, bouncelands

Cutlist/Watchlist:Felidar Sovereign, Emrakul, lab maniac, Gary

M21:Ghostly Pilferer, glorious anthem, idol of endurance, vito, thorn of the dusk rose, speaker of the heavens?, carrion grub, heartfire immolator, griffin aerie, kinetic augur, tolarian kraken, silversmote ghoul, traitorous greed, crypt lurker, hobblefiend, rangers guile, village rites, obsessive stitcher

ZNR: Kabira Takedown, Sejiri Shelter, windrider wizard, Malakir Rebirth, skyclave shadowcat, fireblade charger, kazuul's fury, magmatic channeler, song-mad treachery, iridescent hornbeetle, khalni ambush, vastwood fortification, witch of the moors, chained brute, living Lightning, branching Evolution, thriving lands

Cool combo stuff: Demonic Pact + Harmless Offering. Maybe Aggressive Mining, Slaughter-Priest of Mogis, Final Flare, Dreamshaper Shaman, Magmaw
Ajani's Chosen with Rancor
Freed from the Real or sth similar?
Scholar of the Ages
Riftsweeper?

(Old) Iconic Cards: Secure the Wastes, Descend upon the Sinful, declaration in stone, flickerwisp, nyx-fleece ram, savannah lions,
suture priest, mangara of corondor, daybreak coronet Terror (for the BB) Monastery Swiftspear, flametongue kavu, urabrask, the hidden, ghostfire,
goblin Bombardement, feldon bring to light
For a Counters Theme:https://tappedout.net/users/Endaarr/lists/17-12-19-counters/?cat=color&sort=&fmt=
[https://tappedout.net/users/Endaarr/lists/17-12-19-counters/?cat=color&sort=&fmt=]