msem-instigator

When Hand of the Murder enters, if you control a creature with a +1/+1 counter on it, create a 1/1 black Bird creature token with flying.

Rhapsody {4}{R}{R} (Pay {4}{R}{R} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Menace

Enchant creature
When Hannaru's Courage enters, create a 1/1 white Soldier creature token with vigilance.
Enchanted creature gets +1/+1 and has vigilance.

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Hapless Chronomancer dies, if it had no time counters on it, return target instant or sorcery card from your graveyard to your hand.

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)
Whenever Haploc Blooddrinker becomes blocked, it gains lifelink until end of turn.

When Happily Retired enters, exile target creature you don't control with mana value 3 or less until Happily Retired leaves the battlefield.
{1}, Sacrifice Happily Retired: Return target exiled creature card you own that's on an Adventure to your hand. Activate only as a sorcery.

When Harbinger of Growth enters, create a 1/1 green Saproling creature token.
{1}{G}, Sacrifice Harbinger of Growth: Populate. (Create a token that's a copy of a creature token you control.)

Hard Bargain deals 2 damage to target creature or planeswalker an opponent controls and you gain 2 life. Then if you have more life than that opponent, draw a card.

Civilized — Hard-Working Oxen gets +3/+0 as long as you control an artifact, a creature, and an enchantment.

When Hardened Explorer enters, choose one —
• Destroy target artifact.
• Put a +1/+1 counter on Hardened Explorer. It gains haste.

Enchant creature
Enchanted creature gets +2/+2.
Concord — As long as there are four or more card types among permanents you control, enchanted creature has slipstream. (This creature can't be blocked as long as only creatures with slipstream are attacking.)

Choose one —
• Target creature gets +1/+0 and gains indestructible until end of turn.
• Tap target creature. Put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
• Scry 1, then draw a card.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{3}{G}: Harmonic Recruit gets +2/+2 until end of turn. If you're in a renaissance, it gets +4/+4 until end of turn instead.

Draw two cards. Each opponent draws a card.

Target creature an opponent controls loses all abilities and has base power and toughness 0/1 until end of turn.
Showcase {4}{U} (Then if you cast this for its showcase cost, create a 1/1 red Bard creature token that can't block and exile this. Whenever it attacks, you may cast a free copy of this.)

Harpoon Launching deals 3 damage to any target. Create a 1/1 red Goblin creature token.

When Harpooned Bubbledomer enters, mill four cards.
Harpooned Bubbledomer gets +2/+0 and has menace as long as there are four or more card types among cards in your graveyard.

Reach
Whenever one or more creatures with flying attack, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Harpstring Ranger gets +2/+2 until end of turn. Untap it.

{1}, {T}, Move a -1/-1 counter from another creature onto Harried Apothecary: Each opponent loses 1 life and you gain that much life.

Flying
Harrier's Falcon can't attack or block alone.

Target creature gets +3/-1 until end of turn.
Metamorph {1}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Sacrifice a creature: Harrowing Knight gets +2/+2 until end of turn.

Destroy target colorless nonbasic permanent. Harsh Erosion deals 2 damage to that permanent's controller.

Enchant creature
Enchanted creature gets +2/+0 and has haste.

Harsh Wastes deals 3 damage to target attacking or blocking creature.