A fairly standard 555 card vintage unpowered cube with a few un cards, playtest cards, and custom cards for funsies.
Can optionally add the 10 triomes to improve lands/fixing (I sometimes remove these as they fix for splashy 3-5 color decks too well)
And add 5 kiki-combo cards occasionally.
Optional module to add power to the cube: https://cubecobra.com/cube/list/61f5bd3a84f57c0ff80d8dd4?view=table&scale=medium

Combos to watch out for:

• Persist combos (Persist creature + +1/+1 counters + sac outlet)
• Stoneforge Mystic + Kaldra/Batterskull
• Reanimator(big boi + reanimate spell + discard effect)
• Cheat into play with Sneak/Show/Eureka/flash
• artifact cheat with tinker
• blink value with soulherder/maralka/phelia
• strip mine + land recursion / Gitrog/titania/bontu/timbersaw value
• isochron sceptor locks with counterspell/unexpectedly absent
• evoke elementals with ephemerate/reanimate
• draw punish with narset/sheoldred/bowmasters and power pack draw 7s
• time warp and regrowth effects
• opposition + tokens
• wildfire/upheaval + mana ramp.
• devoted druid / swift recon infinite mana
• Stax with Smokestack, smallpox, contamination, winter orb etc.
• Dark Depths with thespian's stage, trigger happy, sun-wukong, god pharoah's aspirant.

Cube Errata:

• All basic lands are snow lands
• Colorless mana is instead generic mana(for matter reshaper, reality smasher and thought-knot seer). Eldrazi displacer's ability costs 2W.
  The following cards cost 1 less mana to cast:
• God-Eternal Rhonas, moonsnare specialist.
  The following cards are custom made for this cube:
• Goblin tusk-riders, Monastery Bell-Ringer, Grave Exchange, Tombstone Fiend, Solaire of Astora, Falconer Captain, Maralka Blossom Weaver, Lacewing Sprite, Coral Mystic, Mummified Amalgam, Underrealm Tender, Living Loam, Chittering End, dawnbringer pegasus, Genesis Golem, mossgrove guardian, Goblin Raiding Party, end of days, splinter shock, Strange Brew, Rite of the Bloodchief, Storm Fleet Cannoneer, hungering horde, Stroke of Creativity, Glint-horn Celebrant, Yaala Hopes Herald, Artificer's Blade, Rexxar the Beastmaster, Undying Tribute, Ghost Train, Moldervine Beast, Phoenix-Heart Adept, High Hrothgar, siyokoy drowner, dualcaster initiate, arcane tutor, bound in flames, mesmeric gaze, weatherlight Collected legacy, goblin war machine, cogwork guardian, Daka-Daka Chaos Herder, Sakashima Protocol, sea titan, rizzrack the timbersaw, sheik the hidden sage, squirrel squire, commander vimes, ebb // flow, search // destroy, Faelin the Cloudcaller, Vvardenfell, the Imperial City, firelink shrine, Zagreus Underworld Prince, melinoe times nemesis, crystalline formation, Princess Mononoke, sun-wukong heavens equal, spyro the dragon, Zuko the Blue Spirit, Azula fire nation princess, geralt butcher of blaviken, faelin the cloudcaller, phoenix fire, edward fullmetal alchemist,
  link, hero of hyrule, god-pharoah's aspirant.

Cycles of the following:
1 Theros god
1 Amonkhet god
2 evoke elementals
2 adventure cards in storybook frame
1 titan.
1 overlord
1 planeswalker per color combo
2 fetches, 1 dual, 1 shock, 1 utility land (manland or sac/draw land)
5 colored lands, 5 colorless lands in gold book border.