msem-instigator

If a creature entering the battlefield under your control causes a triggered ability of that creature to trigger, you may exile it. If you do, that ability triggers an additional time.

Menace, trample, indestructible
Whenever Aghavaan Unleashed deals combat damage to a player, that player gets that many poison counters.
At the beginning of your end step, sacrifice another creature or transform Aghavaan Unleashed.

{T}: Add {C}.
At the beginning of each end step, if you control five or more Snake creatures, transform Aghavaan's Wound.

[+2]: Create a 1/1 blue Bird creature token with flying.
[–2]: Reveal the top card of your library. If it's an enchantment or land card, put it onto the battlefield. Otherwise, put it in your hand.
[–7]: Draw seven cards.

[+1]: Aiel Tazan deals 2 damage to any target. Then she deals 2 damage to herself unless you have her deal 2 damage to you.
[–3]: Creatures you control get +2/+0 and gain haste until end of turn.
[–X]: Create an X/1 red Elemental creature token with haste and trample. Exile that token at the beginning of the next end step. If X is 6 or more, it gains double strike.

As long as Ajani Enlightened has an odd or even number of loyalty counters on him, he has protection from mana values of that quality.
[+1]: Any number of players may draw a card. You may put a loyalty counter on Ajani Enlightened for each opponent that does.
[0]: You gain 2 life. Untap up to two target lands.
[–8]: Choose odd or even. You get an emblem with “You have protection from mana values of the chosen quality.”

[+1]: Distribute two +1/+1 counters among up to two target creatures. You gain 2 life.
[–1]: Create a 2/2 green Cat Warrior creature token.
[–3]: Exile target creature. Its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.
[–7]: You get an emblem with “Creatures you control get +X/+X, where X is your life total.”

[+1]: Create a 1/1 white Soldier creature token.
[–2]: Until end of turn, target creature you control gets +3/+3 and other creatures you control get +1/+1.
[–8]: You get an emblem with “Each creature you control gets +1/+1 for each other creature you control.”

{T}, Sacrifice a Treasure, Gold, or permanent named Lotus Petal: Add two mana of any one color.
{T}, Sacrifice a Clue or Omen: Scry 2, then draw a card.
{T}, Sacrifice an Idol: Put two +1/+1 counters on target creature.
{T}, Sacrifice a Food: You gain 6 life.
{T}, Sacrifice a Bullet: Alchemos, Efficiency Engine deals 3 damage to any target.

Flying, first strike, vigilance, trample, lifelink
{4}: Put a +1/+1 counter on Alin and Meva, Warqueens.

Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Noncreature spells you cast cost {X} less to cast, where X is All-Encompassing Akvan's power.

[+1]: Until end of turn, All-Enduring Mafua becomes a 5/5 Cat Warrior creature with lifelink and indestructible. (He doesn't lose loyalty while he's not a planeswalker.)
[–2]: Exile target creature.
[–X]: Return each creature card with mana value X from your graveyard to your hand.

[+1]: Create a 1/1 blue Merfolk creature token with “When this creature dies, draw a card, then discard a card.”
[–1]: Target creature gets -2/-0 until your next upkeep and attacks during its controller's next turn if able.
[–7]: You get an emblem with “Creatures your opponents control get -4/-0 and attack each turn if able.”

Whenever a nontoken creature you control dies, create a 1/1 black Spirit creature token with flying.
[+1]: Each opponent loses 2 life and you gain 2 life.
[–2]: You may sacrifice a creature. When you do, destroy target nonland permanent.

Trample
Whenever a creature attacks, Alpha Stag gets +2/+2 until end of turn.

Double strike
Whenever an opponent casts a spell that targets you or a spell or permanent you control, Alrathan Outcast deals damage equal to twice its power to that player.
Alrathan Outcast gets +1/+1 for each Aura and Equipment you control.

Trample
Whenever a Warrior you control dies, it deals 1 damage to any target.

[+2]: Add {R}{R}. Until end of turn, red mana doesn't empty as steps and phases end, and creatures you control gain “{R}: This creature gets +1/+0 until end of turn.”
[–3]: You may cast a monocolored red spell with mana value 6 or less from your hand without paying its mana cost.
[–6]: You may pay any amount of {R}. When you do, Amelie Mayn deals that much damage to each of up to that many different targets.

At the beginning of combat on your turn, if there are seven or more loyalty counters on Ameret, they become a 5/5 Angel creature with flying and indestructible until end of turn.
[+1]: Create a 1/1 red and white Cleric creature token with lifelink and haste.
[–X]: Ameret deals X damage to any target. You gain X life.

As long as it's your turn, Ameret is a 4/4 Angel creature with flying, haste, indestructible, and “Whenever Ameret attacks, attach any number of Equipment you control to them.”
[+2]: Create two 1/1 red and white Cleric creature tokens with lifelink.
[–3]: Ameret deals 4 damage to target creature or planeswalker. You gain 4 life.
[–4]: For each creature you control, create a Weapon token and attach it to that creature. (It's an Equipment artifact with equip {2} and “Equipped creature gets +1/+1.”)

[+1]: Scry 2. Create a 1/1 black Insect creature token with flying.
[–2]: Judge each creature you control.
[–8]: For each card type, search your library and graveyard for a card of that type and exile it, then shuffle. You may play any number of cards exiled this way without paying their mana costs.

When Ancestors' Grace enters, you may search your library for an enchantment card, reveal it, put it into your hand, then shuffle.
Enchantments you control not named Ancestors' Grace have indestructible.
Enchanted permanents you control have indestructible.

Codex — Earthcraft; Enchantress's Presence; Dream Halls; Energy Field; Eldrazi Conscription. (As this enters, conjure its contents into a shuffled face-up additional library.)
You can't draw from this codex's library.
If a permanent you control would explore, you may put a card from this codex's library into your hand instead.

Protection from instants and from sorceries
At the beginning of your upkeep, sacrifice another creature. For each creature sacrificed this way, put a +1/+1 counter on Andazir, the Crownless.
At the beginning of your end step, if you control four or fewer creatures, transform Andazir.

At the beginning of each end step, if you drew and/or discarded six or more cards this turn, return Anemothrys, Reefcrown from your graveyard to the battlefield.
Cycling {R}{G} ({R}{G}, Discard this card: Draw a card.)