Thriving Isle

This land enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

It'll Quench Ya!

Counter target spell unless its controller pays {2}.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Otter-Penguin

Whenever you draw your second card each turn, this creature gets +1/+2 until end of turn and can't be blocked this turn.

Sokka's Haiku

Counter target spell.
Draw a card, then mill three cards.
Untap target land.

Sokka, Lateral Strategist

Vigilance
Whenever Sokka and at least one other creature attack, draw a card.

Tiger-Seal

Vigilance
At the beginning of your upkeep, tap this creature.
Whenever you draw your second card each turn, untap this creature.

Messenger Hawk

Flying
When this creature enters, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
This creature gets +2/+0 as long as you've drawn two or more cards this turn.

Turtle-Seals

Vigilance (Attacking doesn't cause this creature to tap.)

Rowdy Snowballers

When this creature enters, tap target creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

The Blue Spirit

You may cast the first creature spell you cast each turn as though it had flash.
Whenever a nontoken creature you control enters during combat, draw a card.

Whirlwind Technique

Target player draws two cards, then discards a card.
Airbend up to two target creatures. (To airbend a creature, exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)

Island

Knowledge Seeker

Vigilance
Whenever you draw your second card each turn, put a +1/+1 counter on this creature.
When this creature dies, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")