msem-instigator

When Harvest Blighter enters, create a black Aura Curse enchantment token named Rotting Away attached to target player. The token has enchant player and “Whenever a creature enters under enchanted player's control, if it has toughness 2 or greater, put a -1/-1 counter on that creature.”

Harvest (You may tap any number of creatures you control as you cast this spell. If you do, reduce this spell's mana cost by their total power.)
Create a 5/5 colorless Scarecrow artifact creature token with “This creature can't block or harvest.”
Flashback {8}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Reprise {3}{R} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)
Hatsuo's Maneuver deals 1 damage to any target. Create a number of 1/1 red Warrior creature tokens equal to the damage dealt by this spell.

Defender
Civilized — As long as you control an artifact, a creature, and an enchantment, Hauling Hippopotamus can attack as though it didn't have defender.

Deathtouch
Discard a card: Headless Carriage gains indestructible until end of turn. Tap it.
Ride {2}{B}{B} ({2}{B}{B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Target permanent you control gains hexproof until end of turn. If that permanent is a creature, it also gets +1/+1 until end of turn.

Choose a nonland permanent type. Destroy all permanents of the chosen type. Each player who controlled a permanent destroyed this way draws a card.

Equipped creature gets +1/+1 for each card in your hand.
Equip {3}

Rogues and Pirates you control have haste.
Whenever one or more creatures you control deal combat damage to a player, exile the top card of your library. You may play that card this turn.

[+1]: Up to two target creatures you control each get +1/+1 and gain vigilance until end of turn.
[–3]: Create two 1/1 white Dwarf Peasant creature tokens. You gain 2 life.
[–7]: You get an emblem with “Creatures you control get +2/+2 and have double strike.”

When Helicos-Drowned Captain enters, create a black Aura Curse enchantment token named Marked for Death attached to target player. The token has enchant player and “At the beginning of enchanted player's upkeep, that player loses 1 life.”

Choose five target cards in your graveyard. An opponent separates those cards into two piles. Put one pile into your hand and exile the other. Exile Hell or High Water.

At the beginning of each end step, if a creature died this turn, you may put a +1/+1 counter on target creature you control.

Whenever you cast a legendary spell or play a legendary land, put a +1/+1 counter on Henros, Royal Herald and you gain 1 life.
{2}{W}: Look at the top six cards of your library. You may exile a legendary card from among them. Then shuffle. If the exiled card has mana value less than Henros's power, you may put it onto the battlefield tapped. If you don't, put it into your hand.

Elemental, instant, and sorcery spells you cast cost {1} less to cast.

(Transform this if it's not attached to a creature. Pay {B} as a sorcery to unattach it.)
Enchant creature you control
Herald of Death's rider gets +1/+1.
Sacrifice a creature: Herald of Death's rider gets +2/+2 until end of turn.

Beckon Ox {1}{W} ({1}{W}: This enchantment permanently becomes an Ox creature in addition to its other types.)
Vigilance
Whenever a creature or another enchantment you control enters, you gain 1 life.

(Transform this if it's not attached to a creature. Pay {4}{G} as a sorcery to unattach it.)
Enchant creature you control
Herdstrider's rider gets +1/+1 for each land you control and has trample.
Whenever Herdstrider's rider attacks, create an X/X green Elephant creature token with trample that's tapped and attacking, where X is that creature's power. Exile that token at the end of combat.

This spell can't be countered.
Enchant land
At the beginning of combat on your turn, untap enchanted land. It becomes a 6/6 green Lizard creature with haste until end of turn. It's still a land.

Assault {B} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Hilaback Outriders assaults, it gains menace until end of turn.

Civilized — As long as you control an artifact, a creature, and an enchantment, prevent all combat damage that would be dealt to Hirsute Champion.

Reprise {2}{W} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)
You gain 2 life. Then distribute X +1/+1 counters among creatures you control, where X is the amount of life this spell caused you to gain.

When Hitana's Implements enters, draw a card.
{1}, {T}: Add one mana of any color.
Augmented — At the beginning of each end step, if you've spent {W}{U}{B}{R}{G} on spells this turn, exile Hitana's Implements. If you do, create a 5/5 blue Horror creature token.

Other Pirates you control get +1/+0.
Whenever another Pirate you control enters, Hookhand Freebooter deals 1 damage to any target.
When Hookhand Freebooter dies, create a Bullet token. (It's an artifact with “{T}, Sacrifice this artifact: It deals 1 damage to any target.)

As Horizon of Origins enters, you may reveal an Island or Mountain card from your hand. If you don't, Horizon of Origins enters tapped.
{T}: Add {U} or {R}.