Experiment One

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Remove two +1/+1 counters from Experiment One: Regenerate Experiment One. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Ambush Paratrooper

Flash
Flying
{5}: Creatures you control get +1/+1 until end of turn.

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Stalwart Valkyrie

You may pay {1}{W} and exile a creature card from your graveyard rather than pay this spell's mana cost.
Flying

Bone Picker

This spell costs {3} less to cast if a creature died this turn.
Flying, deathtouch

Heron of Hope

Flying
If you would gain life, you gain that much life plus 1 instead.
{1}{W}: Heron of Hope gains lifelink until end of turn.

Martyr's Soul

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.)
When Martyr's Soul enters, if you control no tapped lands, put two +1/+1 counters on it.

Silverbeak Griffin

Flying (This creature can't be blocked except by creatures with flying or reach.)

Inspiring Overseer

Flying
When this creature enters, you gain 1 life and draw a card.

Battle Screech

Create two 1/1 white Bird creature tokens with flying.
Flashback—Tap three untapped white creatures you control. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Nested Shambler

When Nested Shambler dies, create X tapped 1/1 green Squirrel creature tokens, where X is Nested Shambler's power.

Mothrider Patrol

Young Wolf

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Answered Prayers

Whenever a creature you control enters, you gain 1 life. If Answered Prayers isn't a creature, it becomes a 3/3 Angel creature with flying in addition to its other types until end of turn.

Anointed Chorister

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
{4}{W}: Anointed Chorister gets +3/+3 until end of turn.

Segovian Angel

Charmed Stray

Lifelink
When Charmed Stray enters, put a +1/+1 counter on each other creature you control named Charmed Stray.

Guardians' Pledge

White creatures you control get +2/+2 until end of turn.

Squall Drifter

Garruk's Companion

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Healer's Hawk

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Daybreak Chimera

This spell costs {X} less to cast, where X is your devotion to white. (Each {W} in the mana costs of permanents you control counts toward your devotion to white.)
Flying

Elephant Guide

Enchant creature
Enchanted creature gets +3/+3.
When enchanted creature dies, create a 3/3 green Elephant creature token.

Battlefield Raptor

Militia Bugler

Vigilance (Attacking doesn't cause this creature to tap.)
When Militia Bugler enters, look at the top four cards of your library. You may reveal a creature card with power 2 or less from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Bonesplitter

Beloved Princess

Lifelink
Beloved Princess can't be blocked by creatures with power 3 or greater.

Triplicate Spirits

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.)
Create three 1/1 white Spirit creature tokens with flying.

Leonin Skyhunter

Raffine's Informant

When Raffine's Informant enters, it connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

Kor Skyfisher

Flying
When Kor Skyfisher enters, return a permanent you control to its owner's hand.

Loyal Pegasus

Flying
Loyal Pegasus can't attack or block alone.

Vault Skirge

({B/P} can be paid with either {B} or 2 life.)
Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Priest of Ancient Lore

When Priest of Ancient Lore enters, you gain 1 life and draw a card.

Wispmare

Flying
When Wispmare enters, destroy target enchantment.
Evoke {W} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Bayou Groff

As an additional cost to cast this spell, sacrifice a creature or pay {3}.

Dizzying Swoop

Tap up to two target creatures. (Then exile this card. You may cast the creature later from exile.)