Glister Bairn

Vivid — At the beginning of combat on your turn, another target creature you control gets +X/+X until end of turn, where X is the number of colors among permanents you control.

Sanar, Innovative First-Year

Vivid — At the beginning of your first main phase, reveal cards from the top of your library until you reveal X nonland cards, where X is the number of colors among permanents you control. For each of those colors, you may exile a card of that color from among the revealed cards. Then shuffle. You may cast the exiled cards this turn.

Shinestriker

Flying
Vivid — When this creature enters, draw cards equal to the number of colors among permanents you control.

Island

Chaos Spewer

When this creature enters, you may pay {2}. If you don't, blight 2. (To blight 2, put two -1/-1 counters on a creature you control.)

Shimmercreep

Menace (This creature can't be blocked except by two or more creatures.)
Vivid — When this creature enters, each opponent loses X life and you gain X life, where X is the number of colors among permanents you control.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Mountain

Thirst for Identity

Draw three cards. Then discard two cards unless you discard a creature card.

Mischievous Sneakling

Changeling (This card is every creature type.)
Flash

Merrow Skyswimmer

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying, vigilance
When this creature enters, create a 1/1 white and blue Merfolk creature token.

Swamp

Bogslither's Embrace

As an additional cost to cast this spell, blight 1 or pay {3}. (To blight 1, put a -1/-1 counter on a creature you control.)
Exile target creature.

Plains

Forest

Prideful Feastling

Changeling (This card is every creature type.)
Lifelink

Tam, Mindful First-Year

Each other creature you control has hexproof from each of its colors.
{T}: Target creature you control becomes all colors until end of turn.