msem-instigator

Flying (This creature can't be blocked except by creatures with flying or reach.)
Escorted Rider gets +1/+1 as long as you control another creature with flying.

When Zoetic Tomb enters, exile target creature.
{4}: Until end of turn, Zoetic Tomb becomes a Golem artifact creature with power and toughness equal to the exiled creature's base power and toughness.

Whenever Wandering Doyen is dealt damage, it deals that much damage to you.
{4}{R}: Attacking creatures you control get +1/+0 and gain first strike until end of turn.

Put target creature into its owner's library third from the top.

When Matron of Machines dies, put a +1/+1 counter on up to one target creature.
{3}{W}, Exile Matron of Machines from your graveyard: Create two 1/1 colorless Construct artifact creature tokens. Activate only as a sorcery.

Whenever Rustshell Mantis is dealt damage, put that many +1/+1 counters on it. (It must survive the damage to get the counters.)

Menace, haste

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

Enchant land
Enchanted land has “{T}: Each opponent loses 2 life.”

Flying, haste
Whenever you attack with three or more creatures, harmonize three times. (To harmonize, trigger up to one harmony of a permanent you control.)
If you would harmonize, you may instead return Herald of Festivities from your graveyard to your hand.

As Damian, the Boss enters, pay up to 5 life. He enters with that many additional loyalty counters.
[–X]: You gain X plus 3 life.
[–1]: You draw a card and each opponent discards a card.
[–4]: Destroy up to one target creature. Create a 3/3 green Mole creature token.

When Tempting Gate enters, draw a card, then choose a card name.
At the beginning of your end step, you may exile any number of target creatures you control with the chosen name, then return them to the battlefield under your control.

Survivors you control have flying.

Lifelink
Players casting spells and creatures entering don't cause abilities to trigger.

Flying
When Carrier Familiar enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

This spell can't be countered.
If a spell or ability an opponent controls causes you to sacrifice Wellspring of Creation, you may put it on the top or bottom of its owner's library instead of putting it into that player's graveyard.

Create two 1/1 red Goblin creature tokens.

Perfect Aim deals 5 damage to target creature with flying. When that creature dies this turn, you gain 5 life.

Search your library for a land card and put that card onto the battlefield tapped with a venom counter on it. It gains “Whenever this land is tapped for mana, you lose 1 life.” Then shuffle.

Enchant creature
Enchanted creature has distorted. (It can be blocked by tapped creatures but not untapped creatures.)
{1}{B}: Enchanted creature can't block this turn.

Choose one —
• Destroy target artifact or enchantment.
• Target creature you control explores twice. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on that creature, then you may put that card in your graveyard.)

{T}, Pay 1 life: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
At the beginning of your end step, if your life total is less than 5, sacrifice Achet-Aton's Vizier. If you do, create a 4/4 black Demon creature token with flying.

Creatures you control get +2/+0 and gain menace until end of turn. (They can't be blocked except by two or more creatures.)

Flying
Disgraced 4 (This enters with four -1/-1 counters. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
Whenever you put one or more -1/-1 counters on Forgotten Tyrant, it deals that much damage to any target.

Flying, trample, haste
Whenever a land you control enters or a land is put into your graveyard from the battlefield, Skyscreecher Dragon deals 2 damage to each opponent.