msem-instigator

(Add a quest counter as this enters. Sacrifice after 3.)
Once each turn, when you cast a spell with mana value equal to the number of lands you control, you may add a quest counter.
You may search your library for a basic land card, reveal it, then shuffle and put that card on top. You gain 1 life for each quest counter on Hoof Cliff Expedition.
Search your library for a creature card, reveal it, put it into your hand, then shuffle.

{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.

Audition for white. If you create a Role this way, untap the creature it enchants. (Create a 1/1 Construct Actor creature token, a Scout Role giving 2/3 and vigilance, or a Cleric Role giving 2/2 and lifelink. Roles replace older ones.)

Hopeful Healer gets +1/+1 and has lifelink as long as you are glorious. (You are glorious as long as you have a glory counter.)

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

Pressure {3}{B} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Return target creature card from your graveyard to your hand. If this spell was cast for its pressure cost, put that card onto the battlefield instead.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Lifelink

Up to one target creature gains flying until end of turn. (Then exile this card. You may cast the creature later from exile.)

Target creature you control gets +2/+0 until end of turn. If that creature is attacking, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)

This spell costs {1} less to cast for each creature that attacked this turn.
Hot to the Touch deals X damage to any target.

{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 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.

(Transcend as a sorcery to gain that type and a +1/+1 counter.)
{T}, Tap an untapped creature you control: Add one mana of any color.
{G}: Demigod — Whenever you cast a creature spell this turn, draw a card.
{4}{G}{G}: God — Creatures you control get +3/+3 and gain trample until end of turn.

Destroy target Human creature.

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

Humble Fieldhand gets +1/+0 and has vigilance as long as you control an Equipment.

{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.)

Enchant player
For each 1 life enchanted player would gain, you gain 1 life instead unless that player pays {1}.

Target creature you control gets +X/+X until end of turn. It fights target creature you don't control.

Huolin Shrine enters 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.

Enchant creature
When Hypnotic Halo enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
{2}{W}{W}, Sacrifice Hypnotic Halo: Exile enchanted creature.

{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.