Dragon Arch

{2}, {T}: You may put a multicolored creature card from your hand onto the battlefield.

General Ferrous Rokiric

Hexproof from monocolored
Whenever you cast a multicolored spell, create a 4/4 red and white Golem artifact creature token.

Jenson Carthalion, Druid Exile

Whenever you cast a multicolored spell, scry 1. If that spell was all colors, create a 4/4 white Angel creature token with flying and vigilance.
{5}, {T}: Add {W}{U}{B}{R}{G}.

Jund Hackblade

As long as you control another multicolored permanent, Jund Hackblade gets +1/+1 and has haste.

Ink-Treader Nephilim

Whenever a player casts an instant or sorcery spell, if that spell targets only Ink-Treader Nephilim, copy the spell for each other creature that spell could target. Each copy targets a different one of those creatures.

Grixis Grimblade

As long as you control another multicolored permanent, Grixis Grimblade gets +1/+1 and has deathtouch. (Any amount of damage it deals to a creature is enough to destroy that creature.)

Dune-Brood Nephilim

Whenever Dune-Brood Nephilim deals combat damage to a player, create a 1/1 colorless Sand creature token for each land you control.

Naya Hushblade

As long as you control another multicolored permanent, Naya Hushblade gets +1/+1 and has shroud. (It can't be the target of spells or abilities.)

Esper Stormblade

As long as you control another multicolored permanent, Esper Stormblade gets +1/+1 and has flying.

Void Rend

This spell can't be countered.
Destroy target nonland permanent.

Begin the Invasion

Search your library for up to X battle cards with different names, put them onto the battlefield, then shuffle.

Glint-Eye Nephilim

Whenever Glint-Eye Nephilim deals combat damage to a player, draw that many cards.
{1}, Discard a card: Glint-Eye Nephilim gets +1/+1 until end of turn.

Rienne, Angel of Rebirth

Flying
Other multicolored creatures you control get +1/+0.
Whenever another multicolored creature you control dies, return it to its owner's hand at the beginning of the next end step.

Bant Sureblade

As long as you control another multicolored permanent, Bant Sureblade gets +1/+1 and has first strike.

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.

Muldrotha, the Gravetide

During each of your turns, you may play a land and cast a permanent spell of each permanent type from your graveyard. (If a card has multiple permanent types, choose one as you play it.)

Ruinous Ultimatum

Destroy all nonland permanents your opponents control.

Mana Cannons

Whenever you cast a multicolored spell, Mana Cannons deals X damage to any target, where X is the number of colors that spell is.

Guildpact Paragon

Whenever you cast a spell that's exactly two colors, look at the top six cards of your library. You may reveal a card that's exactly two colors from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Invasion of Ravnica

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Ravnica enters, exile target nonland permanent an opponent controls that isn't exactly two colors.

Invasion of Ravnica // Guildpact Paragon

Witch-Maw Nephilim

Whenever you cast a spell, you may put two +1/+1 counters on Witch-Maw Nephilim.
Whenever Witch-Maw Nephilim attacks, it gains trample until end of turn if its power is 10 or greater.

Yore-Tiller Nephilim

Whenever Yore-Tiller Nephilim attacks, return target creature card from your graveyard to the battlefield tapped and attacking.