Call for Unity

Revolt — At the beginning of your end step, if a permanent you controlled left the battlefield this turn, put a unity counter on Call for Unity.
Creatures you control get +1/+1 for each unity counter on Call for Unity.

Authority of the Consuls

Creatures your opponents control enter tapped.
Whenever a creature an opponent controls enters, you gain 1 life.

White Sun's Zenith

Create X 2/2 white Cat creature tokens. Shuffle White Sun's Zenith into its owner's library.

Whitemane Lion

Flash
When Whitemane Lion enters, return a creature you control to its owner's hand.

Anointed Procession

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Knight of the White Orchid

First strike
When Knight of the White Orchid enters, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield, then shuffle.

Angelic Chorus

Whenever a creature you control enters, you gain life equal to its toughness.

Blind Obedience

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

Citizen's Arrest

When Citizen's Arrest enters, exile target creature or planeswalker an opponent controls until Citizen's Arrest leaves the battlefield.

Borrowed Time

When Borrowed Time enters, exile target nonland permanent an opponent controls until Borrowed Time leaves the battlefield.

Elesh Norn, Mother of Machines

Vigilance
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Permanents entering don't cause abilities of permanents your opponents control to trigger.