msem-instigator

When Hand of Fury enters, it gets +2/+2 and gains haste until end of turn.
At the beginning of your upkeep, if your fealty to Mountains is five or greater, transform Hand of Fury. (Each Mountain you control counts towards your fealty to Mountains.)

Equipped creature has menace.
Whenever equipped creature attacks, it gets +X/-X until end of turn, where X is a number of your choice less than its toughness.
Equip {2}

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

Flying, trample
Whenever Hao'Tai, the Ancient One deals combat damage to a player, exile the top four cards of that player's library. Until end of turn, you may cast instant, sorcery, and creature cards from among those exiled cards, and you may spend mana as though it were mana of any color to cast them.

Flying
Whenever Hao'Tai deals combat damage to a player, that player exiles the top five cards of their library and separates them into two piles. Put an ember counter on each card in the pile of your choice. You may play cards from exile with ember counters for as long as they remain exiled.

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)
Whenever Haploc Striker attacks and isn't blocked, you may cast target instant or sorcery card from your graveyard if its mana value is less than or equal to Haploc Striker's power. Exile that card instead of putting it into your graveyard as it resolves.

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

Exile the top three cards of your library. When you do, choose one —
• You may play those cards until the end of your next turn.
• Exchange your hand and the exiled cards.

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

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

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.

Cast this spell only during your turn and only during the declare attackers step or with its acquiesce ability.
Untap all creatures you control. After this phase, there is an additional combat phase.
Acquiesce (If you cast this spell from your hand, exile it as it resolves. When one or more creatures you control deal combat damage to an opponent, you may cast this card from exile without paying its mana cost.)

At the beginning of your upkeep, Harvest the Stars deals 4 damage to any target.

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.)

Discard your hand. Creatures you control get +X/+0 and gain first strike until end of turn, where X is the number of cards discarded this way.

When Hate-Driven Arsonist enters, you may have it deal X damage to target creature or planeswalker, where X is the number of instant and sorcery cards in your graveyard.

Each player discards their hand, then draws cards equal to the greatest number of cards discarded this way.

Reprise {3}{R} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)
Hatsuo's Maneuver deals 1 damage to any target. Create a number of 1/1 red Warrior creature tokens equal to the damage dealt by this spell.

First strike
{1}{R}: Hatsuo, Honored General and other Warrior creatures you control get +1/+0 until end of turn.

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

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever another noncreature source deals damage to a creature or player, you may have Hav'za, Itavan Warchief deal half that damage, rounded up, to any target.

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.)

Menace
At the beginning of your end step, He of All Hallow's Eve deals damage equal to its power to you unless you're horrific. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Head on Collision deals 2 damage to any target.
Leitmotif (If you cast this spell from your hand, exile it as it resolves. When you next cast a spell that shares a color with this card, you may cast this from exile without paying its mana cost.)