msem-instigator

Reveal the top three cards of your library. Put up to one creature or Revelation card from among them into your hand and the rest into your graveyard.
Coalesce {6}{G} (You may cast this from your graveyard for {6}{G}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Hold Life in Taloned Grasp's power is equal to the number of cards in your graveyard.

As Holdsteady Engine enters, choose a card name.
Cards with the chosen name entering the battlefield don't cause abilities to trigger.
Activated abilities of cards with the chosen name can't be activated unless they're mana abilities.

When Hollow Hooligan enters, up to two target creatures can't block this turn.
Mirage {1}{R} (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.)

Defender, deathtouch
Homestead Watcher gets +2/+0 and can attack as though it didn't have defender as long as you control another creature with defender.

Equipped creature has respawn. (When this creature dies, if it attacked this turn, return it to its owner's hand.)
Equip {1}

Target creature you control fights another target creature.
Inscribe {3}{G} ({3}{G}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

{T}: Add {C}.
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

Return a permanent card from your graveyard to your hand.
Motley — If there are five or more names among nonland permanents you control, return two permanent cards from your graveyard to your hand instead.

When Hoof Cliff Caretaker enters, return target card of an opponent's choice from your graveyard to your hand.

(Add a quest counter as this enters. Sacrifice after 3.)
Once each turn, when you cast a spell with mana value equal to the number of lands you control, you may add a quest counter.
You may search your library for a basic land card, reveal it, then shuffle and put that card on top. You gain 1 life for each quest counter on Hoof Cliff Expedition.
Search your library for a creature card, reveal it, put it into your hand, then shuffle.

{T}: Add {C}.
{1}: Hoof Cliff Horngrove becomes a 2/2 Elemental creature until end of turn. It's still a land.
Menagerie — Whenever Hoof Cliff Horngrove becomes a creature, it gains your choice of +1/+1, flying, first strike, lifelink, trample, or haste until end of turn. This ability triggers only if there are five or more creature types among creatures you control.

Trample, haste

Double strike
When a creature scavenges Hook-Style Trainee, put a double strike counter on that creature.
Scavenge {4}{R} ({4}{R}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

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.)

Armed — Whenever Hordedriver Enthusiast attacks, if it's equipped, creatures you control get +1/+0 and gain trample until end of turn.

Trample

Flying, haste
At the beginning of each of your postcombat main phases, you may cast an instant or sorcery card from your graveyard with mana value less than or equal to the number of creatures that dealt combat damage to opponents this turn without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Horizon Wayfarer's power and toughness are each equal to the number of differently named lands you control.

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}.

Trample
Harmony — Put a +1/+1 counter on target Warrior you control. You gain 1 life.
Whenever one or more Warriors you control deal combat damage to a player, harmonize. (Trigger up to one harmony of a permanent you control.)

When Horn of Seasons enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equipped creature gets +3/+0.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

No more than two creatures can attack each combat.

You may put a permanent card from your hand onto the battlefield.
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.)

Haste
When Horse Thief enters, you may gain control of target creature or Steed until end of turn. It gains haste until end of turn. If it's a Steed, attach it to Horse Thief.

When Host of Nature enters, create two 2/2 red and green Elk creature tokens.