At the beginning of your end step, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
4 /
4
{3}
Chromatic Lantern
Artifact
Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.
{3}
Commander's Sphere
Artifact
{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.
{3}{W}{U}{B}{R}{G}
Conflux
Sorcery
Search your library for a white card, a blue card, a black card, a red card, and a green card. Reveal those cards, put them into your hand, then shuffle.
{2}{G}
Cultivate
Sorcery
Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
{1}{U}
Cyclonic Rift
Instant
Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")
{2}{B}{B}
Damnation
Sorcery
Destroy all creatures. They can't be regenerated.
{3}
Darksteel Ingot
Artifact
Indestructible
{T}: Add one mana of any color.
{5}
Door to Nothingness
Artifact
Door to Nothingness enters the battlefield tapped.
{W}{W}{U}{U}{B}{B}{R}{R}{G}{G}, {T}, Sacrifice Door to Nothingness: Target player loses the game.
{3}{G}
Explosive Vegetation
Sorcery
Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
{1}{G}
Farseek
Sorcery
Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.
{5}
Gilded Lotus
Artifact
{T}: Add three mana of any one color.
{5}{R}{R}{R}
Insurrection
Sorcery
Untap all creatures and gain control of them until end of turn. They gain haste until end of turn.
{2}{G}
Kodama's Reach
Sorcery - Arcane
Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
{R}{G}{W}{U}
Kynaios and Tiro of Meletis
Legendary Creature - Human Soldier
At the beginning of your end step, draw a card. Each player may put a land card from their hand onto the battlefield, then each opponent who didn't draws a card.
2 /
8
{1}{W}{B}
Mortify
Instant
Destroy target creature or enchantment.
{1}{W}{U}{B}{R}{G}
O-Kagachi, Vengeful Kami
Legendary Creature - Dragon Spirit
Flying, trample
Whenever O-Kagachi, Vengeful Kami deals combat damage to a player, if that player attacked you during their last turn, exile target nonland permanent that player controls.
6 /
6
{1}{G}
Prismatic Omen
Enchantment
Lands you control are every basic land type in addition to their other types.
{1}{B}{G}
Putrefy
Instant
Destroy target artifact or creature. It can't be regenerated.
{6}
Ramos, Dragon Engine
Legendary Artifact Creature - Dragon
Flying
Whenever you cast a spell, put a +1/+1 counter on Ramos, Dragon Engine for each of that spell's colors.
Remove five +1/+1 counters from Ramos: Add {W}{W}{U}{U}{B}{B}{R}{R}{G}{G}. Activate only once each turn.
4 /
4
{1}{G}
Rampant Growth
Sorcery
Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
{2}{U}
Rhystic Study
Enchantment
Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.
{1}
Sol Ring
Artifact
{T}: Add {C}{C}.
{X}{W}{U}{U}
Sphinx's Revelation
Instant
You gain X life and draw X cards.
{1}{W}{W}{U}
Supreme Verdict
Sorcery
This spell can't be countered.
Destroy all creatures.
{3}{G}
Tempt with Discovery
Sorcery
Tempting offer -- Search your library for a land card and put it onto the battlefield. Each opponent may search their library for a land card and put it onto the battlefield. For each opponent who searches a library this way, search your library for a land card and put it onto the battlefield. Then each player who searched a library this way shuffles.
{8}{U}{U}
Time Stretch
Sorcery
Target player takes two extra turns after this one.
{X}{B}{G}{U}
Villainous Wealth
Sorcery
Target opponent exiles the top X cards of their library. You may cast any number of spells with mana value X or less from among them without paying their mana costs.
{U}{B}{R}{G}
Yidris, Maelstrom Wielder
Legendary Creature - Ogre Wizard
Trample
Whenever Yidris, Maelstrom Wielder deals combat damage to a player, as you cast spells from your hand this turn, they gain cascade. (When you cast the spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom of your library in a random order.)