Iridian Maelstrom

Destroy each creature that isn't all colors.

Conflux

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.

Door to Nothingness

Door to Nothingness enters tapped.
{W}{W}{U}{U}{B}{B}{R}{R}{G}{G}, {T}, Sacrifice Door to Nothingness: Target player loses the game.

Cromat

{W}{B}: Destroy target creature blocking or blocked by Cromat.
{U}{R}: Cromat gains flying until end of turn.
{B}{G}: Regenerate Cromat.
{R}{W}: Cromat gets +1/+1 until end of turn.
{G}{U}: Put Cromat on top of its owner's library.

Ramos, Dragon Engine

Flying
Whenever you cast a spell, put a +1/+1 counter on Ramos 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.

Apex Devastator

Cascade, cascade, cascade, cascade (When you cast this 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 in a random order. Multiple instances of cascade each trigger separately.)

O-Kagachi, Vengeful Kami

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.

Maelstrom Archangel

Flying
Whenever Maelstrom Archangel deals combat damage to a player, you may cast a spell from your hand without paying its mana cost.

Progenitus

Protection from everything
If Progenitus would be put into a graveyard from anywhere, reveal Progenitus and shuffle it into its owner's library instead.

Maelstrom Nexus

The first spell you cast each turn has cascade. (When you cast your first 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 in a random order.)

Garth One-Eye

{T}: Choose a card name that hasn't been chosen from among Disenchant, Braingeyser, Terror, Shivan Dragon, Regrowth, and Black Lotus. Create a copy of the card with the chosen name. You may cast the copy. (You still pay its costs.)

Jared Carthalion

+1: Create a 3/3 Kavu creature token with trample that's all colors.
−3: Choose up to two target creatures. For each of them, put a number of +1/+1 counters on it equal to the number of colors it is.
−6: Return target multicolored card from your graveyard to your hand. If that card was all colors, draw a card and create two Treasure tokens.
Jared Carthalion can be your commander.

Karona, False God

Haste
At the beginning of each player's upkeep, that player untaps Karona, False God and gains control of it.
Whenever Karona attacks, creatures of the creature type of your choice get +3/+3 until end of turn.

Leyline of the Guildpact

If Leyline of the Guildpact is in your opening hand, you may begin the game with it on the battlefield.
Each nonland permanent you control is all colors.
Lands you control are every basic land type in addition to their other types.

Chromanticore

Bestow {2}{W}{U}{B}{R}{G} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Flying, first strike, vigilance, trample, lifelink
Enchanted creature gets +4/+4 and has flying, first strike, vigilance, trample, and lifelink.

Primeval Spawn

If Primeval Spawn would enter and it wasn't cast or no mana was spent to cast it, exile it instead.
Vigilance, trample, lifelink
When Primeval Spawn leaves the battlefield, exile the top ten cards of your library. You may cast any number of spells with total mana value 10 or less from among them without paying their mana costs.

Genju of the Realm

Enchant land
{2}: Enchanted land becomes a legendary 8/12 Spirit creature with trample until end of turn. It's still a land.
When enchanted land is put into a graveyard, you may return Genju of the Realm from your graveyard to your hand.

Two-Headed Dragon

Flying
Menace (This creature can't be blocked except by two or more creatures.)
Two-Headed Dragon can block an additional creature each combat.
{1}{R}: Two-Headed Dragon gets +2/+0 until end of turn.

Legacy Weapon

{W}{U}{B}{R}{G}: Exile target permanent.
If Legacy Weapon would be put into a graveyard from anywhere, reveal Legacy Weapon and shuffle it into its owner's library instead.