msem-instigator

Flying
When Tormentor Harpy enters, if there are three or more creature cards in your graveyard, target creature an opponent controls gets -3/-3 until end of turn.

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature can't attack or block.
At the beginning of your upkeep, you gain 1 life.

When Basalt Ritualist enters, you may sacrifice a land or exile a land card from your graveyard. When you do, exile target creature, instant, or sorcery card from your graveyard. Until the end of your next turn, you may play that card. If that spell would be put into a graveyard, exile it instead.

Sacrifice Amateur Auteur: Destroy target enchantment.

Destroy target non-Elf creature. Its controller loses 1 life for each Elf you control.

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

Trample, vigilance
You may cast Iteration Devourer from your graveyard by exiling seven other cards from your graveyard in addition to paying its other costs.

Creatures can't attack you or a planeswalker you control unless their controller pays {2} for each of those creatures.
Creatures can't block Ghastly Scraper unless their controller pays {2} for each of those creatures.

{1}, Discard a card: Painted Watcher gets +1/+1 and becomes the color of your choice until end of turn.

Enchant player
When Curse of Slaughter enters, it deals 4 damage to target creature or planeswalker enchanted player controls.
Creatures attacking enchanted player have trample.

When Infested Goblin dies, choose target creature. At the beginning of your next upkeep, that creature's controller sacrifices it.

When Hired Kalak enters, put target card from your graveyard on top of your library.

Enchant land
Enchanted land has “{T}: Add one mana of any color.”
{3}, Sacrifice Alpha Trial: Conjure a card named Test Run into your hand. (It's a sorcery that costs {X}{G} with “Create an X/X green Mutant creature token. Draw a card.”)

Detain target creature. (Until your next turn, that creature can't attack or block and its activated abilities can't be activated.)
Scry 1.

Whenever Solvent Tide attacks, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Equipped creature and creatures you control that share a name with it get +1/+0.
Whenever equipped creature attacks, create a tapped and attacking token that's a copy of that creature, except it's not legendary. Exile that token at the beginning of the next end step.
Equip {2}

As Brave the Issbarrens enters, choose a color.
White creatures you control have protection from the chosen color. (This permanent can't be targeted, dealt damage, enchanted, or equipped by anything with that color.)

Ruins Pack gets +2/+2 as long as you sacrificed a permanent this turn.

Trample
Whenever Forthright Wrecker deals combat damage to a player or noncreature permanent, it deals that much damage to each other planeswalker controlled by defending player and each other battle protected by defending player.

First strike

Whenever you gain life for the first time each turn, create a 1/1 white Cleric creature token.

{1}{B}, Sacrifice a creature: You gain 1 life and draw a card.
{4}{B}, Pay 3 life, Sacrifice Traverse the Endless Well: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Flying, haste
Whenever Cheng attacks, look at the top six cards of your library. You may reveal a creature card from among them and put it into your hand. If it's a Dragon, put it onto the battlefield tapped and attacking instead. Put the rest on the bottom of your library in a random order.

Tap up to two target creatures an opponent controls. Those creatures don't untap during their controller's next untap step.
Create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Flash
Whenever you cast your second spell each turn, put a +1/+1 counter on Brooding Replacement.