msem-instigator

Whenever one or more creatures you control deals combat damage to a player, you may sacrifice one of them. When you do, destroy target creature defending player controls, then you and the destroyed creature's controller draw a card.

Trample
When Arpechian Bellowers enters, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Search your library for a green creature card, reveal it, put it into your hand, then shuffle.

Lands you control have hexproof.
{2}{G}{U}: Rouse 2. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

When Arpechian Stag enters, create a 3/3 red Elk creature token with haste, a 3/3 green Elk creature token with trample, and a 3/3 white Elk creature token with vigilance.

Deathtouch
Whenever another creature dies, you get a glory counter. (You lose glory counters before life. A player with ten or more glory counters wins the game.)
{4}{B}, {T}: Destroy target creature and Arrogant Entrant.

Arsenal Curator gets +1/+1 as long as you control a Plains.
{2}{W}: Untap target creature you control. It gets +0/+1 until end of turn.

{T}: Add {C}.
Harmony — Add one mana of any color.
{1}, {T}: Harmonize. (Trigger up to one harmony of one permanent you control.)

Exile up to two target permanents you control, then return those cards to the battlefield under your control.

Draw two cards. You may cast an instant or sorcery spell with mana value X or less from your hand without paying its mana cost, where X is the number of cards in your hand.

Counter target spell unless its controller pays {1}. If you control an artifact, instead counter that spell unless its controller pays {4}.

When Artillery Mage enters, it deals 5 damage to target creature you don't control.
{5}{R}, {T}, Discard a card: Artillery Mage deals 5 damage to target creature you don't control.

Whenever you cast a noncreature spell, creatures you control get +1/+0 until end of turn.

{T}: Draw a card. Artisan's Fountain doesn't untap during its controller's next untap step.

Flying
Clerics you control are Angels in addition to their other types.
Attacking Angels you control get +1/+0.

Flying
Clerics you control are Demons in addition to their other types.
Attacking Demons you control have deathtouch.

Flash
When Ascetic of Imbalance enters, draw two cards, then discard two cards. If you discarded two cards that don't share a type, Ascetic of Imbalance deals 2 damage to any target.

Flying
When Ascetic of the Folded Fan 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.”)
Each creature you control with a +1/+1 counter on it has vigilance.

Whenever you cast an Inscription spell, you may choose target creature you control. If you do, as that Inscription resolves, exile it inscribed onto that creature instead of putting it anywhere else.

Equipped creature gets +2/+2.
Art of war — At the beginning of your end step, if equipped creature dealt damage to an opponent this turn, target nonbasic land an opponent controls doesn't untap during its controller's next untap step.
Equip {2}

Whenever Ashen Host becomes the target of a spell, Ashen Host deals 2 damage to any target.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This creature can't be sacrificed.

Haste
{T}, Sacrifice a creature: Ashspeaker deals 1 damage to any target.

Flying
When Aspect of Divinity dies, create a 0/2 red Egg creature token with “When this creature dies, return target creature card with mana value 2 or less from your graveyard to the battlefield.”

Creatures with power greater than Aspiring Recluse's can't block it.
Whenever Aspiring Recluse deals combat damage to a player, you may pay {2}. If you do, transform it.

Target player sacrifices an attacking creature.
Bulwark — That player sacrifices two attacking creatures instead if you control a creature with toughness 4 or greater.