msem-instigator

Whenever you cast a spell during an opponent's turn, Haughty Priest deals 1 damage to that player.

{1}{B}, Pay 2 life: Moonlight Butcher gains menace until end of turn.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
Deadland Mongrel gets +1/+1 if it engorged a creature card with power 3 or greater.

Haste
{1}{W}: Fellor Heartstriker gains lifelink until end of turn.

Injustice deals 4 damage to target creature. Post a bounty on up to one other target creature. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

Counter target spell with mana value 3 or less. If a spell is countered this way, return it to its owner's hand instead of putting it anywhere else.

Renown 2 (When this creature deals combat damage to a player, if it isn't renowned, put two +1/+1 counters on it and it becomes renowned.)
When Blind Sharpshooter becomes renowned, it deals 2 damage to target creature defending player controls.

Whenever you sacrifice an Idol, put a +1/+1 counter on Orchard Botanist.

Once each turn, when you sacrifice a permanent, you may put two progress counters on Ceaseless Research and surveil 2.
{2}{G}, Remove X progress counters from Ceaseless Research: Create an X/X green Mutant creature token. X can't be less than 3. Activate only as a sorcery.

[+1]: Add {C}. Spend this mana only to cast artifact or colorless spells.
[0 ]: Create a 1/1 colorless Construct artifact creature token.
[–2]: Look at the top six cards of your library. You may reveal an artifact or colorless card from among them and put it into your hand. Put the rest on the bottom in a random order.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Vigilance, trample
{G}{W}: Demon — Abwad Kahroba gains “At the beginning of combat on your turn, you may put a +1/+1 counter on another target creature.”
{X}{G}{W}: Elder — Create X 2/1 black Horror creature tokens. You gain X life.

Whenever Anima Interrogator attacks, defending player reveals a card at random from their hand.

Exile up to one target card from a graveyard. If you do, create a 1/1 green Spirit creature token.
Coalesce {7}{G} (You may cast this from your graveyard for {7}{G}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

When Tempting Shahmaran enters, gain control of target creature. Untap it and it gains haste. At the beginning of the next end step, exile that creature and put X +1/+1 counters on Tempting Shahmaran, where X is that creature's power.
Tempting Shahmaran has all activated abilities of cards exiled with it.

Ward—Discard a card. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player discards a card.)
You have “Ward—Discard a card.”

Enchant artifact or creature
When Dilapidate enters, tap enchanted permanent.
Enchanted permanent loses all abilities and doesn't untap during its controller's untap step.

Haste
Whenever Herald of the Humble deals combat damage to a player, that player reveals the top card of their library. If it's a nonland card with mana value 3 or less, they may cast it without paying its mana cost.

Archive 5 (As this enters, shuffle the top five cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
If you would draw a card from an archived library, draw a card from each of your archived libraries instead. (Archived libraries are those that still have their Study in play.)

{T}, Sacrifice a creature: Return target creature card from your graveyard to your hand.
{T}, Sacrifice an artifact: Planar Processor deals 1 damage to any target.
{T}, Sacrifice an enchantment: Draw a card.
{T}, Sacrifice a land: Add one mana of any color.

When Nettlehowler enters, exile up to one target card from a graveyard.
If a creature dealt damage by Nettlehowler this turn would die, exile it instead.

Haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Vengeant Precursor. It gains trample until end of turn.

As Humble Abode enters, choose a creature or planeswalker type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast spells of the chosen type.

Each creature you control with a +1/+1 counter on it has trample.
{1}{R}{G}: Pyresong Aspirant deals 1 damage to target creature. You may have that creature gain hexproof until end of turn.

Flash
Advance {3}{W} (Cast this for {3}{W} to advance it as it enters. {3}{W}: Advance this as a sorcery.)
Whenever Steelwoven Soldier advances, it gets +2/+2 until end of turn.

Whenever an artifact or enchantment you control enters, target player mills two cards.