msem-instigator

If a permanent with spirited entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

When Indomitable Duo enters, choose up to two creature card names.
Whenever Indomitable Duo attacks, put a +1/+1 counter on each creature you control with a name chosen by Indomitable Duo.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{1}, {T}: Choose a nonland card name. Reveal the top three cards of your library and put each revealed card with that name into your hand. Put the rest into your graveyard.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{W}{B}: Create a 0/1 white and black Human Advisor creature token with “When this creature enters, target creature can't attack or block until this creature leaves the battlefield.”

Flash
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{W}{B}: Kirishima's Escort gets +1/+1 and gains first strike until end of turn.

Flash
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{1}: Remove target attacking creature you control from combat and untap it.

Whenever you activate an ability of a creature that isn't a mana ability, Moranai Tracker gets +1/+1 until end of turn.

At the beginning of your upkeep, if Nightmare Riders is in your graveyard, you may mill two cards.

Whenever you cast an instant or sorcery spell from your hand, you may cast target card with the same name as that spell from your graveyard. (You still pay its costs.)

Whenever Shina Taiyohata or another creature you control enters, you may have that creature gain haste. If you do, return that creature from the battlefield to its owner's hand at the beginning of the next end step.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{R}{W}: Creatures you control gain flying and haste until end of turn.

Spirited (When this enters, you may activate one of its activated abilities without paying its cost.)
{1}, {T}: Add one mana of any color. When you do, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Spirited (When this enters, you may activate one of its activated abilities without paying its cost.)
{3}, {T}: Create a colorless Equipment artifact token with “Equipped creature gets +1/+1” and equip {1}. Attach that token to a creature you control.

Equipped creature gets +0/+3.
Whenever equipped creature dies, draw a card.
Equip {3}

Equipped creature gets +1/+1.
Equipped creature has “When this creature dies, if it's not a token, create a token that's a copy of it except it's a colorless Spirit Dragon with flying in addition to its other abilities.”
Equip {2}

Activated abilities of cards in your graveyard cost {2} less to activate.

You may have Terracotta Legion enter as a copy of any creature with mana value 1 or less you control, except it's an artifact in addition to its other types.

Whenever equipped creature attacks, you may unattach Throwing Stones. When you do, target creature can't block this turn.
Equip {3}

When Warfan of Changing Winds enters, draw a card.
Whenever a card you own is exiled from anywhere, you may put it on the bottom of your library.

Chamber of Splendor enters tapped.
When Chamber of Splendor enters, you may pay {1}. If you do, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
{T}: Add {C}.

{T}, Sacrifice Palace of Reflections: Choose a land you control. Search your library for a land card with the same name as the chosen land, put it onto the battlefield tapped, then shuffle.

{T}: Add {C}.
As long as Shengin Heartland is in your graveyard, lands you control have “{T}: Add {G} or {U}.”

As Animus, Life's Entropy enters, choose a color.
You and Animus each have hexproof from the chosen color.
Attain {6} ({6}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Hexproof
You have hexproof.
If a source would deal damage to you, prevent 1 of that damage.
{1}, Sacrifice two permanents: Draw two cards. Activate only during your turn.

Creatures you control get +1/+1 until end of turn.
Lifecycle {3} ({3}, Discard this card: Create two tapped 1/1 colorless Elemental creature tokens.)