Preston, the Vanisher

Whenever another nontoken creature you control enters, if it wasn't cast, create a token that's a copy of that creature, except it's a 0/1 white Illusion.
{1}{W}, Sacrifice five Illusions: Exile target nonland permanent.

Valor in Akros

Whenever a creature you control enters, creatures you control get +1/+1 until end of turn.

Distinguished Conjurer

Whenever another creature you control enters, you gain 1 life.
{4}{W}, {T}: Exile another target creature you control, then return it to the battlefield under its owner's control.

Flicker of Fate

Exile target creature or enchantment, then return it to the battlefield under its owner's control.

Plains

Brightmare

When this creature enters, tap up to one target creature. You gain life equal to that creature's power.

Faith's Fetters

Enchant permanent
When this Aura enters, you gain 4 life.
Enchanted permanent can't attack or block, and its activated abilities can't be activated unless they're mana abilities.

Thriving Heath

This land enters tapped. As it enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Inspiring Overseer

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

Valorous Steed

Vigilance (Attacking doesn't cause this creature to tap.)
When this creature enters, create a 2/2 white Knight creature token with vigilance.

Settle Beyond Reality

Choose one or both —
• Exile target creature you don't control.
• Exile target creature you control, then return it to the battlefield under its owner's control.

Rambunctious Mutt

When this creature enters, destroy target artifact or enchantment an opponent controls.

Restoration Angel

Flash
Flying
When this creature enters, you may exile target non-Angel creature you control, then return that card to the battlefield under your control.

Cavalry Drillmaster

When this creature enters, target creature gets +2/+0 and gains first strike until end of turn. (It deals combat damage before creatures without first strike.)