Bant Sureblade

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

Knight of New Alara

Each other multicolored creature you control gets +1/+1 for each of its colors.

Snow-Covered Mountain

Scuttlemutt

{T}: Add one mana of any color.
{T}: Target creature becomes the color or colors of your choice until end of turn.

Snow-Covered Island

Grixis Grimblade

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

Might of the Nephilim

Target creature gets +2/+2 until end of turn for each of its colors.

Snow-Covered Forest

Psychotic Fury

Target multicolored creature gains double strike until end of turn.
Draw a card.

Civic Saber

Equipped creature gets +1/+0 for each of its colors.
Equip {1}

Jund Hackblade

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

Esper Stormblade

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

Snow-Covered Swamp

Snow-Covered Plains

Naya Hushblade

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

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.