msem-instigator

When Harshapal Banner enters, create three 1/1 white Soldier creature tokens with vigilance.
Equipped creature gets +2/+2.
Equip {3}

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.)

Menace
Art of war — At the beginning of your end step, if Hashiro's Infiltrator dealt damage to an opponent this turn, that player discards a card.

When Hatewracked Explorer enters, you may sacrifice an artifact or creature. If you do, crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)
{4}{B}{R}, Sacrifice an artifact or creature: Destroy target creature if it was dealt damage this turn.

When Haughty Paladin enters, you may sacrifice another artifact or creature. If you do, tap all creatures your opponents control.

Whenever you cast a spell during an opponent's turn, Haughty Priest deals 1 damage to that player.

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.

{W}: Target creature assigns combat damage equal to its toughness rather than its power this turn.

When Haunted Heirloom dies, create a Treasure token.

When Haunted Hermit enters, choose one —
• Put a +1/+1 counter on Haunted Hermit.
• Create a 1/1 white Spirit creature token with flying.

Whenever Haunted Prodigy attacks, you may tap target creature.
Unveil {2}{W}{U} ({2}{W}{U}: Transform this. Unveil only as a sorcery.)

{W}, Sacrifice Haunting Bard: Destroy target artifact or enchantment.

Enchant creature
Enchanted creature gets -1/-3.

Whenever Haunting Maestro attacks, you may tap or untap up to two target creatures.

Flying, lifelink

Scavenge {5}{U} ({5}{U}, 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.)

Haste (This creature can attack and {T} as soon as it comes under your control.)
Mirage {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.)

Hazy Summits enters tapped.
{T}: Add {R} or {W}.
{1}, {T}: Add one mana of any color.

Put target creature on top of its owner's library.
Quickdraw {2}{U} (When a creature you control blocks or becomes blocked, you may cast this spell for {2}{U}.)

Reach
When Headhunter Mantis enters, if a creature you controlled died this turn, create a 1/1 green Insect creature token.

You gain 5 life, then you may regenerate target creature. (The next time this would be destroyed this turn, it isn't. Instead tap it.)

When Healing Center enters, you gain 2 life.
{T}: Add {C}.

When Healing Potion enters, scry 1, then draw a card.
{2}, {T}, Sacrifice Healing Potion: You gain 4 life.

Menace
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{R}: Another target creature you control gains menace until end of turn.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{X}{R}: Hearth Dweller gets +X/+0 until end of turn.