msem-instigator

Menace
Whenever an opponent activates an ability of a permanent, if it isn't a mana ability, Howling Shieldbreaker deals 2 damage to that permanent or player.

Advance {3}{W} (Cast this for {3}{W} to advance it as it enters. {3}{W}: Advance this as a sorcery.)
Whenever Hrexa Enforcer advances, put a +1/+1 counter on it.

Whenever an opponent casts a spell, if no mana was spent to cast it or it has mana value greater than the number of lands that player controls, counter that spell.
{G/W}, Sacrifice this creature: Citizens and Peasants you control get +1/+1 and gain indestructible until end of turn.

When this creature enters, create a 2/2 black Zombie creature token. That token seeks secrets and gains haste until end of turn. (Give it that Oath Aura. Fulfill it by attacking with it and two or more other creatures to draw a card.)

Flying, haste
Whenever a battle you control is defeated, you may return Huma of Glory from your graveyard to the battlefield.

Humble Fieldhand gets +1/+0 and has vigilance as long as you control an Equipment.

When Humored Outlaw enters, choose one —
• Put a +1/+1 counter on Humored Outlaw. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
• Destroy target artifact or enchantment.

Menace
Other Zombies you control get +1/+1.
Whenever a Zombie you control dies, each opponent loses 1 life.

Whenever an opponent casts a spell during your turn, Hunter of Incantations deals 2 damage to that player.

Vigilance
When Huolin Sanctifier dies, if it was in a pack, create a 2/1 black Spirit creature token with “This creature can't block.” (Two or more creatures you control with equal power are in a pack.)

Whenever Hurried Scavenger attacks or blocks, you may mill two cards.
Hurried Scavenger gets +4/+4 as long as you have five or more card types among cards in your graveyard.

Creatures you control have “{T}: Add {C} or one mana of any of this creature's colors.”
Attain {5}{G} ({5}{G}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Flash
When Icecrowned Fox enters, you may return target spell or permanent to its owner's hand.
Each untapped creature you control has “Ward—Discard a card.” (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player discards a card.)

You may have Icefang Wurm assign its combat damage as though it weren't blocked.
{4}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)

Whenever Icepeak Phantasm becomes the target of a spell or ability, an opponent may pay {2}. If they do, sacrifice it.

When Ichi-no-Oni enters, each player loses 2 life.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Idleglen Instructor enters, draw a card, then discard a card.

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, Iken Troubleshooter deals 2 damage to each opponent.

Whenever Illumination Savant attacks, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Put a +1/+1 counter on each artifact creature and enchantment creature you control.

{G}: Exile target card from a graveyard. If a creature card with flying is exiled this way, put a flying counter on Illustrious Qilin. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

You may have Imaginative Dreamer enter as a copy of any creature on the battlefield. When it does, it stops being a copy.

Imisti enters with a concoction counter on it for each land card in your graveyard.
{1}{G}, Remove any number of concoction counters from Imisti: You gain that much life.
{3}{B}, Remove any number of concoction counters from Imisti: It deals that much damage to target creature or planeswalker.

Whenever Imisti, Elven Insurgent attacks, mill two cards. When you do, you may return target land card from your graveyard to your hand.
{X}{B}{G}: If Imisti has no +1/+1 counters on it, put X +1/+1 counters on Imisti. Activate only as a sorcery.

Haste
Whenever a nonbasic land becomes untapped, its controller loses 1 life.

First strike
When Imperial Dragoon enters, target creature gets +2/+0 until end of turn.