msem-instigator

Flash
Flying
Whenever H13 Wasp enters or you cast an another spell with flash or an instant, exile up to one target nonland permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Flying
If a source you control would deal noncombat damage to a permanent or player, you may have it deal damage equal to Hadak's power instead.

Hafiq the Wise has hexproof as long as you've cast a spell this turn.
{U}, Discard a card with mana value X: Counter target spell with mana value X.
{U}, Sacrifice another permanent with mana value X: Return target instant or sorcery card with mana value X from your graveyard to your hand.

Indestructible
Whenever Hannaru the Conqueror attacks, put a +1/+1 counter on each creature you control.

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.

Trample
As an additional cost to cast creature spells, you may sacrifice a permanent. If you do, that spell costs {2} less to cast and that creature enters with an additional +1/+1 counter on it.

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.

Whenever you cast an instant or sorcery spell from your hand, put that card onto the battlefield face down as a 2/2 creature instead of putting it into your graveyard as it resolves.
Whenever a face-down creature you control deals combat damage to an opponent, you may exile it. If you do, you may cast it without paying its mana cost.

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.

Whenever you cast a black spell, you may exile target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step.
Whenever you cast a red spell, you may have Haunted Sunseeker deal 1 damage to each creature.

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

Untap all other Elves you control during each other player's untap step.
You may cast spells as though they had flash.

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

Menace
When Heart of the Deadwood enters, destroy up to one target creature, then put up to one target creature card from a graveyard onto the battlefield under your control.

Flying, vigilance, deathtouch, lifelink

Flying
When Heartless Host enters, arm target creature. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

Flying, lifelink

Trample
Whenever Heir to the Old Bonds becomes the target of a spell or ability you control for the first time each turn, put a +1/+1 counter on it.

When Helicos Aberration enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

When Helicos-Drowned Captain enters, create a black Aura Curse enchantment token named Marked for Death attached to target player. The token has enchant player and “At the beginning of enchanted player's upkeep, that player loses 1 life.”

Whenever you scry, you gain life equal to the number of cards looked at while scrying this way.

Whenever Herald of Earth deals combat damage to a player, draw a card.
Whenever you draw a card, put a +1/+1 counter on Herald of Earth.

Flying
Whenever Herald of Flame attacks, gain control of target permanent until end of combat. If it's a creature, you may have it become tapped and attacking.
Whenever a creature you control becomes blocked, Herald of Flame deals 3 damage to the player or planeswalker that creature is attacking.

Trample
At the beginning of your end step, if there are two or more +1/+1 counters among creatures you control, return Herald of Might from your graveyard to the battlefield.

Flying
Whenever Herald of Shadow attacks, another target creature can't be blocked this turn.
Whenever a creature you control deals combat damage to an opponent, exile the top card of that player's library. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast it.