Plains

Soul Warden

Whenever another creature enters, you gain 1 life.

Altar of the Brood

Whenever another permanent you control enters, each opponent mills a card.

Ivy Lane Denizen

Whenever another green creature you control enters, put a +1/+1 counter on target creature.

Devoted Druid

{T}: Add {G}.
Put a -1/-1 counter on Devoted Druid: Untap Devoted Druid.

Blasting Station

{T}, Sacrifice a creature: Blasting Station deals 1 damage to any target.
Whenever a creature enters, you may untap Blasting Station.

Vizier of Remedies

If one or more -1/-1 counters would be put on a creature you control, that many -1/-1 counters minus one are put on it instead.

Suture Priest

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Midnight Guard

Whenever another creature enters, untap Midnight Guard.

Scurry Oak

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.)
Whenever one or more +1/+1 counters are put on Scurry Oak, you may create a 1/1 green Squirrel creature token.

Forest

Unnatural Predation

Target creature gets +1/+1 and gains trample until end of turn.

Blossoming Defense

Target creature you control gets +2/+2 and gains hexproof until end of turn.

Order of the Stars

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

Presence of Gond

Enchant creature
Enchanted creature has "{T}: Create a 1/1 green Elf Warrior creature token."

Genesis Wave

Reveal the top X cards of your library. You may put any number of permanent cards with mana value X or less from among them onto the battlefield. Then put all cards revealed this way that weren't put onto the battlefield into your graveyard.

Moon-Blessed Cleric

Divine Intervention — When Moon-Blessed Cleric enters, you may search your library for an enchantment card, reveal it, then shuffle and put that card on top.

Quillspike

{B/G}, Remove a -1/-1 counter from a creature you control: Quillspike gets +3/+3 until end of turn.

Hall of the Bandit Lord

Hall of the Bandit Lord enters tapped.
{T}, Pay 3 life: Add {C}. If that mana is spent on a creature spell, it gains haste.

Doomed Traveler

When Doomed Traveler dies, create a 1/1 white Spirit creature token with flying.