msem-instigator

First strike
Art of war — At the beginning of your end step, if Teikoku Cavalry dealt damage to an opponent this turn, put a +1/+1 counter on it.

Creature tokens you control get +1/+1.
Whenever Thyra, Winter's Warden enters or attacks, you may pay {1}{G/W}. If you do, create Bruga, a legendary 2/2 green and white Wolf creature token.

{4}{W}{W}: Create a 4/4 white Angel creature token with flying.
{2}{W}{W}: Populate. (Create a token that's a copy of a creature token you control.)

Double strike
Whenever an Equipment you control enters, create a 3/3 white Archon creature token with flying and attach that Equipment to that token.

Other Rebel creatures you control get +0/+1.
When Veteran Renegade enters, create a 1/1 white Rebel creature token.

Adorned — Visserine's Royal Guard has lifelink as long as it's equipped and/or enchanted.

Flying
Whenever another creature you control enters, you may have Waxing Celestial get +1/+1 until end of turn.

When Wayfaring Swindler enters, destroy all permanents attached to target creature.

Lifelink
Spells your opponents cast cost an additional {1} to cast for each spell they've cast before it this turn.

When Adept Electromancer enters, scry 2, then reveal the top card of your library. If it's an instant or sorcery card, put it into your hand.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Flying
As long as there are five or more different creature types among creatures you control, Adventuring Guildmage gets +1/+0 and has hexproof.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
When Arbiter of Shal'Iv enters, adjudicate. (Create a white enchantment Aura token with enchant creature and “Sacrifice this token: Untap enchanted creature” attached to target creature.)

When Arcanomancer enters, return up to one target instant card and up to one target sorcery card from your graveyard to your hand.

{1}{U}: Target creature you control can't be blocked this turn by creatures with less power.
{1}{U}: Target creature you control can't be blocked this turn by creatures with greater power.

Flying
When Cerulean Curtain Treasurer enters, audition for blue, then audition for blue again. (Create a 1/1 Construct Actor creature token, a Wizard Role giving 2/2 and prowess, or a Warlock Role giving 2/1 and flying. Roles replace older ones.)

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
Spells you cast that share a type with the card Chillwhisper Witch engorged cost {1} less to cast.

Flying
{2}{U}: Until end of turn, target creature has your choice of base power and toughness 1/1 or 4/4 until end of turn. Activate only outside of combat.

Flying
Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)

Flying
When Cloudshaper enters, return a permanent you control to its owner's hand.

When Coincutter Fence enters, starting with you, each player may create a 2/1 red Rogue creature token with “This creature can't block.” For each opponent that does, create a Treasure token.

Flying
At the beginning of each opponent's end step, if you drew a card this turn, you get a glory counter. (You lose glory counters before life. A player with ten or more glory counters wins the game.)

Harmony — Target player mills four cards.
When Creeping Pianist enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Vigilance
Whenever Disgruntled Student deals combat damage to a player, scry 2.

Defender
When Dispossessed Noble enters, draw a card.