msem-instigator

At the beginning of your upkeep, put a +1/+1 counter on Heyu, Immortal Hunter.
Whenever Heyu becomes the target of a spell or ability an opponent controls, counter it if Heyu has the greatest power among creatures on the battlefield.

Hibernation Den enters tapped.
{T}: Add {W}.
{W}, {T}: You gain 1 life. Activate only as a sorcery and only if you control a white creature.

{1}{G}, Discard Hibiscus Snapdragon: Create a Treasure token.
Scavenge {4}{G} ({4}{G}, 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.)

Scry 2, then create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Monument {2}{R} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

{T}, Sacrifice Hidden Garden Entrance: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Monument {W}{U}{B}{R}{G} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

{T}, Pay 1 life: Add {G} or {U}.
{1}, {T}, Sacrifice Hidden Hollow: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Hidden Prowess deals 2 damage to target creature. When that creature dies this turn, create a 1/1 red Elemental creature token.

Flash
When Hidden Sprout enters, put a +1/+1 counter on target creature.

Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)
{T}: Add {G}.
Whenever Hierarch Ranger encourages a creature, add one mana of any color.

Prowess
Whenever High Rollers Croupier attacks, you may put a lore counter on a Saga you control.

Flash
Prowess
When High Rollers Esteemed enters, you may choose new targets for target spell or ability unless its controller has High Rollers Esteemed deal 4 damage to them.

When Highbeam Hulk enters, you may discard a card. If you do, draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

({T}: Add {R}.)
As Highland Dunes enters, you may pay 1 life. If you don't, Highland Dunes enters tapped.

Concord — Highland Hermit gets +1/+1 and has hexproof as long as there are four or more card types among permanents you control.

({T}: Add {R} or {G}.)
Highland Vale enters tapped.

{T}: Add {G}.
Dominance — {T}: Add {G}{G}. Activate only if you control the creature with the greatest power or tied for the greatest power.

Flash
If a spell or ability an opponent controls would cause you to discard a creature card, you may put that card onto the battlefield instead.

Whenever Highpeak Rider attacks, search your library for a land card and put it onto the battlefield, then shuffle. Sacrifice that land at the beginning of the next end step.

Highpoint Shrine enters tapped unless you played it from exile.
{T}: Add {W} or {U}.

Wanderlust — Whenever Highwild Survivalist attacks, add {R} or {G}. If you control four or more differently named lands, add {R}{G} instead. Until end of turn, you don't lose mana added this way as steps and phases end.

This spell can't be countered.
Enchant land
At the beginning of combat on your turn, untap enchanted land. It becomes a 6/6 green Lizard creature with haste until end of turn. It's still a land.

Whenever a creature you control dies, put a soul counter on Hill of Souls.
{T}: Add {C}.
{T}, Remove a soul counter from Hill of Souls: Add one mana of any color.

When Himari enters, put a +1/+1 counter on a creature you control.
Creatures you control with counters on them have base power and toughness 4/4 and have trample.

Reach
Art of war — At the beginning of your end step, if Hinode Ranger dealt damage to an opponent this turn, put a +1/+1 counter on it.

{2}{R}, {T}, Exert Hinterland Ritualist, Sacrifice another creature: Hinterland Ritualist deals damage equal to the sacrificed creature's power to any target. Activate only as a sorcery. (An exerted creature won't untap during your next untap step.)