msem-instigator

This spell costs {1} less to cast for each storied permanent you control. (Enchantments and legendary permanents are storied.)
Counter target spell.
Draw a card.

Creatures you don't control get -1/-1.
Mirage {1}{B} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
[+2]: Look at the top three cards of your library. Put one of them into your hand and exile the rest.
[–3]: Exile target creature. You may return it to the battlefield under its owner's control.
[–9]: Return any number of creature cards exiled with Lazaire to the battlefield under your control. Then exile any number of target creatures.

Antu, Sun Spirit can't attack or block unless you control ten or more permanents.
As long as it's your turn, other creatures you control get +X/+0 and have haste, where X is the amount of life you've gained this turn.
When Antu dies or is put into exile from the battlefield, you may put him into his owner's library third from the top.

Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1.

Colossal 4—{8} (You may cast this for its colossal cost to have it enter with four +1/+1 counters; or pay {8} as a sorcery: Put four +1/+1 counters on it if it has none.)
Abilities you activate that aren't mana abilities cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Flash
Flying

Enchant creature
When Anxious Worries enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

[0]: Choose up to one target creature. You may put two +1/+1 counters on it, a +1/+1 counter on it and a loyalty counter on Aoia, Monarch of Beauty, or two loyalty counters on Aoia.
[–2]: Exile target creature, then return it to the battlefield. For each kind of counter on it before it left, put that many of that kind of counter on it.
[–9]: You get an emblem with “If an effect would put one or more counters on a permanent you control, it puts five times that many of those counters on that permanent instead.”
Aoia can be your commander.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Art of war — At the beginning of your end step, if Aokara Duelists dealt damage to an opponent this turn, put a +1/+1 counter on it.

Flash
When Aokara Redeemer enters, exile another target permanent you control. Return that card to the battlefield under your control at the beginning of the next end step.

Draw three cards. You gain 3 life. Apex deals 3 damage to any target.

Vigilance, trample
Whenever another Horror you control enters, choose one —
• Destroy target artifact or enchantment.
• You gain 4 life.
• Apex Abomination fights another target creature.

Sacrifice a creature. Draw cards equal to its power and gain life equal to its toughness. (Then exile this card. You may cast the creature later from exile.)

At the beginning of your upkeep, if an opponent controls more creatures than you, you may reveal the top seven cards of your library. Target opponent chooses a creature card revealed this way. Put that card onto the battlefield, and the rest into your graveyard.

Create an 8/8 blue Kraken creature token with hexproof.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

Flying
When Apogee Cranes enters, 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.”)

Apostle of the Elders has lifelink as long as it has a +1/+1 counter on it.

Whenever Apostle of the Spirit Moon becomes blocked by a creature, Apostle of the Spirit Moon deals 1 damage to that creature and that creature's controller.

Apothecary's Gift deals 5 damage to target creature or planeswalker. You gain life equal to the excess damage dealt this way.

At the beginning of your upkeep, if you control ten or more storied permanents, you win the game. (Enchantments and legendary permanents are storied.)

Escalate {2} (Pay this cost for each mode chosen beyond the first.)
Choose one or more —
• Search your library for a card, put it into your hand, then shuffle.
• Return target card from your graveyard to your hand.
• Add {B}{B}{G}{G}.

When Apprentice Summoner enters, search your library for a creature card with mana value 1 or less, put it onto the battlefield, then shuffle.

At the beginning of your end step, put an encroachment counter on Approach of Old Lovi, then it deals X damage to any target and you gain X life, where X is the number of encroachment counters on Approach of Old Lovi.

As Approach the Dark Tomb enters, choose life or death.
• Life — Whenever you cast a creature spell, you may pay 1 life. If you do, draw a card.
• Death — Whenever a creature you control dies, you may pay 1 life. If you do, draw a card.