msem-instigator

Once each turn, when Atal, the Shroudmaker enters or you attack with one or more Horrors, you may create two tapped 1/1 colorless Human creature tokens. If Atal isn't a token, creatures you control gain flying until end of turn.
{2}{W}{W}, Discard Atal: Create a token that's a copy of Atal, the Shroudmaker, except it's 4/4 and isn't legendary. Activate only as a sorcery.

Flying, vigilance
At the beginning of your end step, return up to one target permanent card from your graveyard to the battlefield with an indestructible counter on it.

You may exert Awoken Elemental as it attacks. When you do, Awoken Elemental fights another target creature. (An exerted creature won't untap during your next untap step.)

Menace
Whenever a creature you control deals combat damage to a permanent, that permanent's controller sacrifices it.

Menace
When Azuma Hashiro, the Thronebreaker enters, you may cast up to two cards from your opponents' graveyards without paying their mana costs. If those spells would be put into a graveyard, exile that card instead.

This spell costs {1} less to cast for each creature that attacked this turn.

Trample
{T}: Add {C}.
At the beginning of your upkeep, you may pay {2}. When you do, Blundering Clocktower becomes a creature in addition to its other types until the beginning of your next end step. End the turn.

At the beginning of your end step, if Bramblemane didn't attack this turn, transform it.

Flying, trample
Whenever Bretala of Redsky attacks, it gains double strike until end of turn unless defending player sacrifices a creature.

Trample
{2}{G}{G}: Put Canal Lurker from its owner's graveyard on top of its owner's library.

Flying, haste
When Cataclysmic Skytyrant enters, sacrifice all other non-Dragon creatures you control. For each creature sacrificed this way, create a 3/3 red Dragon creature token with flying.

As Chromatic Interloper enters, choose two abilities from among first strike, menace, vigilance, trample, or haste.
Creatures you control with mana value 5 or greater have the chosen abilities.

Flying, prowess
When Chronosphere Sovereign enters, nonbasic permanents target opponent controls don't untap during their controller's next untap step.
When Chronosphere Sovereign dies, it deals 3 damage to each tapped creature you don't control. Destroy each tapped artifact you don't control.

Search your library for up to two basic land cards, reveal those cards, and put one onto the battlefield tapped and the other into your hand, then shuffle.
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.)

Return up to one target creature card from a graveyard to the battlefield under your control.
Coalesce {9}{B} (You may cast this from your graveyard for {9}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Indestructible

Dekinn, Depths Spirit can't attack or block unless a player has lost 3 or more life this turn.
At the beginning of each player's upkeep, that player may create a Mountain token. If they do, Dekinn deals 3 damage to them.
When Dekinn dies or is put into exile from the battlefield, you may put him into his owner's library third from the top.

Menace
When Depraved Archknight enters, each opponent may pay 7 life. For each player that doesn't, you draw seven cards.

Trample
Creatures your opponents control get -1/-0.

Flying, menace
When Dreadfire Tyrant enters, target opponent reveals their hand. You may put a creature or planeswalker card from it onto the battlefield under your control. That permanent gains haste and “At the beginning of your end step, sacrifice a permanent you control.”
When Dreadfire Tyrant dies, each opponent loses 5 life. You gain life equal to the life lost this way.

Deathtouch, lifelink
When Emperor Azuma Hashiro enters, gain control of target creature for as long as you control Emperor Azuma Hashiro.
At the beginning of your upkeep, each opponent loses life equal to the number of permanents you control but don't own.

Trample
{1}{G}{W}, Discard Enduring Force: Search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle.
{G}{W}: Return Enduring Force from your graveyard to your hand. Activate only as a sorcery.

Once each turn, when Eruq, the Flamebearer enters or you attack with one or more Horrors, you may have Eruq deal 2 damage to each opponent. Then if Eruq isn't a token, gain control of target creature an opponent controls until end of turn. Tap it. It's attacking its controller.
{2}{R}{R}, Discard Eruq: Create a token that's a copy of Eruq, the Flamebearer, except it's 4/4 and isn't legendary. Activate only as a sorcery.

Reach, trample
Revive {4}{G} ({4}{G}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Flying, vigilance, indestructible
Faradia, Honored Sovereign can't attack or block unless you tap three other untapped creatures and/or artifacts you control.

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Fogborn Mauler enters or leaves the battlefield, you gain 2 life.