Shiren

"Truly, I know nothing of the ways of fighting, but I do know some white magic."

Shelinda, Yevon Acolyte

Lifelink
Whenever another creature you control enters, put a +1/+1 counter on that creature if its power is less than Shelinda's power. Otherwise, put a +1/+1 counter on Shelinda.

"The glow is the combination of all your past lives, focusing their energy through your body."
—Avatar Roku

Enter the Avatar State

Until end of turn, target creature you control becomes an Avatar in addition to its other types and gains flying, first strike, lifelink, and hexproof. (A creature with hexproof can't be the target of spells or abilities your opponents control.)

Warriors

Foo Foo Cuddlypoops didn't look much like a saber-tooth moose-lion to Sokka, but his mother certainly did.

Saber-Tooth Moose-Lion

Reach
Forestcycling {2} ({2}, Discard this card: Search your library for a Forest card, reveal it, put it into your hand, then shuffle.)

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.")

"My shirshu can smell a rat a continent away."

June, Bounty Hunter

June can't be blocked as long as you've drawn two or more cards this turn.
{1}, Sacrifice another creature: Create a Clue token. Activate only during your turn. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Airbender Ascension

When this enchantment enters, airbend up to one target creature.
Whenever a creature you control enters, put a quest counter on this enchantment.
At the beginning of your end step, if this enchantment has four or more quest counters on it, exile up to one target creature you control, then return it to the battlefield under its owner's control.

Cursed Mirror

{T}: Add {R}.
As this artifact enters, you may have it become a copy of any creature on the battlefield until end of turn, except it has haste.

"Look at the crowd, folks!"
—Blitzball announcer

Generous Patron

When this creature enters, support 2. (Put a +1/+1 counter on each of up to two other target creatures.)
Whenever you put one or more counters on a creature you don't control, draw a card.

"Yevon is embodied by eternal, unchanging continuity, summoner. Those who question these truths—they are traitors!"

Damning Verdict

Destroy all creatures with no counters on them.