msem-instigator

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
Whenever a creature you control blocks or becomes blocked, it gets +1/+1 until end of turn for each +1/+1 counter on it.

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Honorable Mentor mentors a creature, that creature and Honorable Mentor each gain first strike until end of turn.

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

Other Pirates you control get +1/+0.
Whenever another Pirate enters the battlefield under your control, 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.)

Menace
Whenever Hope Wrangler attacks, target attacking creature with lesser power gains menace until end of turn.

Flying
Morph {4}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When you turn Hopebringer Cherub face up, creatures you control get +1/+1 until end of turn.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Pressure {U} (You may cast this spell for its pressure cost if there are seven or more cards in your graveyard.)

When Horizon Gazer enters the battlefield, reveal the top two cards of your library. Put a noncreature card revealed this way into your hand and the rest into your graveyard.
Ascend {3}{G} ({3}{G}: Exile this creature, then return it to the battlefield transformed. Ascend only as a sorcery.)

Trample

Haste
When Horse Thief enters the battlefield, 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.

{T}: Hotblooded Sorcerer deals 1 damage to target player or planeswalker.
Attain {3}{R} ({3}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Whenever you make first contact, Hotshot Renegade deals 2 damage to up to one target creature or planeswalker. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Flying
When Hoverbike Courier enters the battlefield, you may reappropriate. If you do, draw a card. (To reappropriate, exile exactly two cards from your hand and/or graveyard.)

When Howler Sheriff enters the battlefield, gain control of up to one target creature with a bounty counter on it until end of turn. Untap that creature. It gains haste until end of turn.

When Humble Shepherd enters the battlefield, create a 0/1 white Sheep creature token.
{T}, Tap an untapped Sheep you control: Add one mana of any color.

When Humored Outlaw enters the battlefield, choose one —
• Put a +1/+1 counter on Humored Outlaw.
• Destroy target artifact or enchantment.

At the beginning of each opponent's end step, that player loses 1 life for each creature they control unless they sacrifice a creature. Then they lose 1 life for each card in their hand unless they discard a card.

Menace
Other Zombies you control get +1/+1.
Whenever a Zombie you control dies, each opponent loses 1 life.

You may cast Hunter of the Moon-Serpent from your graveyard as long as you gained life this turn.

Reach
Deploy 3 (As this enters, you may tap any number of other creatures you control with total power 3 or more.)
When Hunting Company enters deployed, destroy target creature with flying.

Hurtling Swine attacks each combat if able.

{1}{W}: Artifact creatures you control get +1/+1 until end of turn. Activate only once each turn.

Whenever IG-2 Disassembler enters the battlefield or attacks, you may sacrifice an artifact. When you do, IG-2 Disassembler deals 2 damage to target player or planeswalker.

Flash
When Icecrowned Fox enters the battlefield, you may return target spell or permanent to its owner's hand.
Each untapped creature you control has “Ward—Discard a card.” (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player discards a card.)

You may have Icefang Wurm assign its combat damage as though it weren't blocked.
{4}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)