msem-instigator

Abandoned Hideout enters tapped if you control another nonbasic land.
{T}: Add {U} or {R}.

Counter target spell. Scry 1.

Instant and sorcery spells you cast cost {1} less to cast.
{U}, {T}, Exile three instant and/or sorcery cards from your graveyard: Draw a card.

You may put a creature or Revelation card from your hand onto the battlefield. Exile that permanent if it would leave the battlefield. If it's a Revelation, it enters as a Horror creature.
Coalesce {7}{U}{U} (You may cast this from your graveyard for {7}{U}{U}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

As Amber Hills enters, you may pay 2 life. If you don't, Amber Hills enters tapped.
{T}, Sacrifice Amber Hills: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

Choose target opponent. Scry 3, then reveal the top card of your library. The chosen player discards an amount of cards equal to that card's mana value. (To scry 3, look at the top three cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)

Exile target creature if its controller controls more lands than you.
Cycling {2} ({2}, Discard this card: Draw a card.)

You may exert Migrating Herd as it attacks. When you do, sacrifice a land and draw a card. (An exerted creature won't untap during your next untap step.)

Other creatures you control get +1/+0.
{R}{W}: Create a 1/1 red and white Warrior creature token. That token gains haste. Exile it at the beginning of the next end step. Activate only as a sorcery.

You may have Snowfield Doppelganger enter as a copy of any creature on the battlefield, except it has “While a player is choosing targets as part of casting a spell, that player must choose at least one other creature that shares a name with this creature if able.”

This spell costs {2} more to cast for each target beyond the first.
Choose one or more —
• Anax's Endeavor deals 2 damage to any target.
• Destroy target nonbasic land. Its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.
• Destroy target artifact. Scry 1.

Deathtouch
Whenever another creature dies, its controller discards a card at random.

Whenever a noncreature permanent enters, Petaldiver deals 1 damage to that permanent's controller.

You may sacrifice three artifacts rather than pay this spell's mana cost.
Exile three artifact cards from your graveyard: Return Salvage Titan from your graveyard to your hand.

Activated abilities of nonland permanents cost {2} more to activate.

Whenever Fleshwarper or another Horror you control dies, each opponent loses 1 life and you gain 1 life. You may mill a card.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Paygan Archer dies, it deals damage to target player or planeswalker equal to its power.

Investigate, then target creature gets -1/-1 until end of turn for each Clue you control. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

When Sable Evangelist enters, create a 0/1 black Cultist creature token with “{1}{B}{B}, Sacrifice three Cultists: Create a 5/5 black Demon creature token.”
Cultists you control get +2/+0 and can't block.

{T}: Draw a card. Activate only if you created a token this turn.

If a card would be put into an opponent's graveyard from anywhere, instead that card is revealed and put on the bottom of that player's library.
Unveil {3}{G}{W} ({3}{G}{W}: Transform this. Unveil only as a sorcery.)

Counter target spell. Create a 1/1 blue Elemental creature token with flying.

Flash
Flying
As long as an opponent controls more creatures than you, Arbiter of the Scales gets +2/+2 and has first strike and lifelink.

This spell costs {2} less to cast if a creature died under your control this turn.
Flying