Plains

Mana Tithe

Counter target spell unless its controller pays {1}.

Sandstone Bridge

Sandstone Bridge enters tapped.
When Sandstone Bridge enters, target creature gets +1/+1 and gains vigilance until end of turn.
{T}: Add {W}.

Secluded Steppe

Secluded Steppe enters tapped.
{T}: Add {W}.
Cycling {W} ({W}, Discard this card: Draw a card.)

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.

Journey to Nowhere

When Journey to Nowhere enters, exile target creature.
When Journey to Nowhere leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Soul Warden

Whenever another creature enters, you gain 1 life.

Akroan Skyguard

Flying
Heroic — Whenever you cast a spell that targets Akroan Skyguard, put a +1/+1 counter on Akroan Skyguard.

Healer's Hawk

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

Auramancer

When Auramancer enters, you may return target enchantment card from your graveyard to your hand.

Fragmentize

Destroy target artifact or enchantment with mana value 4 or less.

Ethereal Armor

Enchant creature
Enchanted creature gets +1/+1 for each enchantment you control and has first strike.

Righteous Charge

Creatures you control get +2/+2 until end of turn.

Squadron Hawk

Flying
When Squadron Hawk enters, you may search your library for up to three cards named Squadron Hawk, reveal them, put them into your hand, then shuffle.

Cartouche of Solidarity

Enchant creature you control
When Cartouche of Solidarity enters, create a 1/1 white Warrior creature token with vigilance.
Enchanted creature gets +1/+1 and has first strike. (It deals combat damage before creatures without first strike.)

Hyena Umbra

Enchant creature
Enchanted creature gets +1/+1 and has first strike.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Celestial Flare

Target player sacrifices an attacking or blocking creature of their choice.

Bonesplitter

Sunlance

Sunlance deals 3 damage to target nonwhite creature.

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.