Quirion Elves

As this creature enters, choose a color.
{T}: Add {G}.
{T}: Add one mana of the chosen color.

Kabira Evangel

Whenever this creature or another Ally you control enters, you may choose a color. If you do, Allies you control gain protection from the chosen color until end of turn.

Diamond Mare

As this creature enters, choose a color.
Whenever you cast a spell of the chosen color, you gain 1 life.

Oona, Queen of the Fae

Flying
{X}{U/B}: Choose a color. Target opponent exiles the top X cards of their library. For each card of the chosen color exiled this way, create a 1/1 blue and black Faerie Rogue creature token with flying.

Voice of All

Flying
As this creature enters, choose a color.
This creature has protection from the chosen color.

Painter's Servant

As this creature enters, choose a color.
All cards that aren't on the battlefield, spells, and permanents are the chosen color in addition to their other colors.

Iona, Shield of Emeria

Flying
As Iona enters, choose a color.
Your opponents can't cast spells of the chosen color.

Diamond Knight

Vigilance (Attacking doesn't cause this creature to tap.)
As this creature enters, choose a color.
Whenever you cast a spell of the chosen color, put a +1/+1 counter on this creature.

Seht's Tiger

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, you gain protection from the color of your choice until end of turn. (You can't be targeted, dealt damage, or enchanted by anything of the chosen color.)

Order of the Stars

Defender (This creature can't attack.)
As this creature enters, choose a color.
This creature has protection from the chosen color.

Pentarch Paladin

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
As this creature enters, choose a color.
{W}{W}, {T}: Destroy target permanent of the chosen color.