Evolving Adaptive

This creature enters with an oil counter on it.
This creature gets +1/+1 for each oil counter on it.
Whenever another creature you control enters, if that creature has greater power or toughness than this creature, put an oil counter on this creature.

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 this creature: Regenerate it. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Fyndhorn Elves

Delighted Halfling

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a legendary spell, and that spell can't be countered.

Scavenging Ooze

{G}: Exile target card from a graveyard. If it was a creature card, put a +1/+1 counter on this creature and you gain 1 life.

Sakura-Tribe Elder

Sacrifice this creature: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Haywire Mite

When this creature dies, you gain 2 life.
{G}, Sacrifice this creature: Exile target noncreature artifact or noncreature enchantment.

Quirion Ranger

Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Birds of Paradise

Mirkwood Spider

Deathtouch
Whenever this creature attacks, target legendary creature you control gains deathtouch until end of turn.

Llanowar Elves

Yisan, the Wanderer Bard

{2}{G}, {T}, Put a verse counter on Yisan: Search your library for a creature card with mana value equal to the number of verse counters on Yisan, put it onto the battlefield, then shuffle.

Acidic Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, destroy target artifact, enchantment, or land.

Elvish Mystic

Caustic Caterpillar

{1}{G}, Sacrifice this creature: Destroy target artifact or enchantment.

Sylvan Safekeeper

Sacrifice a land: Target creature you control gains shroud until end of turn. (It can't be the target of spells or abilities.)