msem-instigator

Reveal the cards in your library. Target opponent chooses three nonland cards with different names from it. You put the chosen cards into your hand. Then shuffle.

Once each turn, when Rova, the Fleshweaver enters or you attack with one or more Horrors, you may put a +1/+1 counter on each creature you control. Then if Rova isn't a token, untap each land you control. Until your next turn, you may cast permanent spells as though they had flash.
{2}{G}{G}, Discard Rova: Create a token that's a copy of Rova, the Fleshweaver, except it's 4/4 and isn't legendary. Activate only as a sorcery.

Defender (This creature can't attack.)
{W}, {T}: You gain 1 life.

{2}{B}{B}, Exile Reclusive Augur from your graveyard: Return another target creature card from your graveyard to the battlefield. Activate only during your turn.

Flying
Concord — When Archangel of Accord enters, if there are four or more card types among permanents you control, destroy all other creatures.

When Crinster Blacksmith enters, nourish 2. (To nourish 2, either put two +1/+1 counters on this creature or create two 1/1 white Citizen creature tokens.)

Scornful Flames deals 4 damage to target player.
Dominance — Scornful Flames deals 1 damage to each creature that player controls if you control the creature with the greatest power or tied for the greatest power.

Target creature becomes the color or colors of your choice until end of turn.
Draw a card.

Salome's Messenger enters tapped.
Whenever you cast your second spell each turn, you may return Salome's Messenger from your graveyard to your hand.

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

Deathtouch
{3}{G}: Deathcoil Cobra gains indestructible until end of turn.

Flying
Ward—Pay 3 life.
Landfall — Whenever a land you control enters, Valakut Hellkite deals 3 damage to any target.

Destroy target creature with flying.

When Dawson's Loot enters, mill two cards, then draw a card.
{1}, {T}, Sacrifice Dawson's Loot: Add one mana of any color.

{1}{B}, Sacrifice a creature or enchantment: Draw a card.
{4}{B}{B}, {T}: Return target creature or enchantment card from your graveyard to the battlefield with a veil counter on it. That permanent gains “If this permanent would leave the battlefield, exile it instead.”

When Churning Spellroot enters, create three 1/1 black Worm creature tokens.

{T}, Pay 1 life: Add {B} or {G}.
{1}, {T}, Sacrifice Seedy Bar: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Harsh Wastes deals 3 damage to target attacking or blocking creature.

Whenever Heedless Astronaut attacks, it gets +2/+0 and gains indestructible until end of turn.

Whenever an opponent discards a card, exile it. You may cast that card as long for as it remains exiled, and you may spend black mana as though it were mana of any color to cast that spell.

Vigilance
{2}, {T}: Target player mills two cards.

Flash
When Adiran Distractor enters, return up to one target creature you control and up to one target creature you don't control to their owners' hands.

[+1]: Tap up to one target nonland permanent. It doesn't untap during its controller's next untap step, and its activated abilities can't be activated until it becomes untapped.
[–4]: Target player skips their next untap step.
[–8]: Exile all tapped permanents.

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)
Whenever Venomous Haploc becomes blocked, other creatures you control gain deathtouch until end of turn.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{1}, Sacrifice a creature: Draw a card. Each opponent loses 1 life and you gain 1 life.
Whenever you sacrifice a creature, if you're in a renaissance, each opponent sacrifices a creature. This ability triggers only once each turn.