msem-instigator

{T}: Add {C}.
{T}, Reappropriate: Add {B} or {R}. (To reappropriate, exile exactly two cards from your hand and/or graveyard.)

(Transform this if it's not attached to a creature. Pay {B} as a sorcery to unattach it.)
Enchant creature you control
Herald of Death's rider gets +1/+1.
Sacrifice a creature: Herald of Death's rider gets +2/+2 until end of turn.

(Transform this if it's not attached to a creature. Pay {4}{G} as a sorcery to unattach it.)
Enchant creature you control
Herdstrider's rider gets +1/+1 for each land you control and has trample.
Whenever Herdstrider's rider attacks, create an X/X green Elephant creature token with trample that's tapped and attacking, where X is that creature's power. Exile that token at the end of combat.

Heretic's Home enters the battlefield tapped.
{T}: Add {R} or {G}.
When Heretic's Home enters the battlefield, you may put a loyalty counter on a planeswalker you control.

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

{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.”)

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

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

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

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.

Hiroto's Refuge enters the battlefield tapped.
When Hiroto's Refuge enters the battlefield, you may mill two cards.
{T}: Add {G} or {W}.

{T}: Add {C}.
{1}: Hoof Cliff Horngrove becomes a 2/2 Elemental creature until end of turn. It's still a land.
Menagerie — Whenever Hoof Cliff Horngrove becomes a creature, it gains your choice of +1/+1, flying, first strike, lifelink, trample, or haste until end of turn. This ability triggers only if there are five or more creature types among creatures you control.

When you attain Hopeless Lanonshee, create two 1/1 black Construct artifact creature tokens.
Whenever a creature dies, each opponent loses 1 life and you gain 1 life.

As Horizon of Origins enters the battlefield, you may reveal an Island or Mountain card from your hand. If you don't, Horizon of Origins enters the battlefield tapped.
{T}: Add {U} or {R}.

{T}: Target player exiles a card from their graveyard. If they do, you gain 1 life.

{T}: Add {C}.
{1}, {T}, Sacrifice House of Forgotten Whispers: Draw a card.

Hozen Shrine enters the battlefield tapped.
{T}: Add {U} or {B}.
{U/B}, {T}, Sacrifice Hozen Shrine: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

As Humble Abode enters the battlefield, choose a creature or planeswalker type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast spells of the chosen type.

Humble Bridge enters the battlefield tapped.
{T}: Add {R} or {W}.
When Humble Bridge enters the battlefield, you may put a loyalty counter on a planeswalker you control.

{T}: Add {C}.
Ascend—Tap ten untapped permanents you control. (Tap ten untapped permanents you control: Exile this land, then return it to the battlefield transformed. Ascend only as a sorcery.)

Huolin Shrine enters the battlefield tapped.
{T}: Add {R} or {W}.
{R/W}, {T}, Sacrifice Huolin Shrine: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

{T}: Add {C}.
{3}{U}: Until end of turn, I's Observatory becomes a 1/4 creature. It's still a land. It has menace if {B} was spent to activate this ability, has first strike if {R} was spent, and assigns combat damage equal to its toughness rather than its power if {G} was spent.

Ice Path enters the battlefield tapped.
As Ice Path enters the battlefield, choose a color.
You may spend {C} as though it were mana of the chosen color.
{T}: Add {C}.

{T}: Add {C}.
{2}: Idravir becomes a 2/2 creature with undying in addition to its other types until end of turn. (When that creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)