msem-instigator

First strike
Whenever you discard a card, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

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

As an additional cost to cast this spell, sacrifice a permanent.
When Harriet, Liberated Wildborn enters, you may remove all counters from target permanent.

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.)

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

Hartwin, Cunning Lieutenant can't block.
If spell or ability would cause an opponent to discard a card, instead that player discards a card at random. When a nonland card with mana value 2 or less is discarded this way, you may cast it without paying its mana cost.

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature enters under an opponent's control, you may have that player lose 1 life.

Prevent all damage that would be dealt to target player this turn.
Fabled {1}{W}{W}{W} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

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.)

Flying, lifelink

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

Gain control of target attacking creature until end of turn. Untap it. It gains indestructible until end of turn.

Trample
Whenever you cast a noncreature spell, crystallize. If you create a Treasure this way, Heartforge Savant deals 1 damage to you for each Treasure you've created this turn. (Put a +1/+1 counter on a creature you control or create a Treasure.)

At the beginning of your upkeep, if you have less life than an opponent, you lose 1 life and you draw a card.

Menace
Sacrifice a Goblin: Heartless Warleader gets +2/+2 until end of turn.

Augmented — Whenever you cast a spell from your hand, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, exile cards from the top of your library until you reveal a nonland card with mana value less than that spell's mana value. You may cast that card without paying its mana cost. Put the revealed cards not cast this way on the bottom of your library in a random order.

Creature spells you cast cost {1} less to cast.

Reach

Whenever you scry, you gain 1 life for each card you looked at while scrying this way.

Whenever a creature blocks, Heat of Battle deals 1 damage to that creature's controller.

You may exert Heavenly Bull as it attacks. When you do, it gains indestructible until end of turn. (An exerted creature won't untap during your next untap step.)
{3}{G}{W}: Destroy all nonland permanents with mana value 3 or less. Activate only if Heavenly Bull is attacking and only once.

Tap up to two target creatures.
Coalesce {5}{W}{W} (You may cast this from your graveyard for {5}{W}{W}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Heavens Claim Their Due enters tapped.