msem-instigator

{T}, Sacrifice Hazy Lagoon: Search your library for a Plains or Island card and put it onto the battlefield tapped, then shuffle.

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.)

At the beginning of your end step, exile target permanent.
When Head of Ulko leaves the battlefield, return each other card exiled with it to the battlefield under your control.

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.)

When Healing Center enters, you gain 2 life.
{T}: Add {C}.

When Healing Potion enters, scry 1, then draw a card.
{2}, {T}, Sacrifice Healing Potion: You gain 4 life.

Heart of Carü Mapu enters tapped.
{T}: Add X mana in any combination of colors, where X is the number of basic land types among lands you control.

At the beginning of your upkeep, create a 1/1 green Saproling creature token.
Whenever a creature you control dies, put a +1/+1 counter on Heart of Spores.
{X}{G}: Move X +1/+1 counters from Heart of Spores onto target creature. Activate only as a sorcery.

{T}: Add {C}.
Wanderlust — {T}: Add one mana of any color. Activate only if you control four or more differently named lands. If you control seven or more, you may add three mana of that color instead.

Cast this spell only if you control a legendary creature or if you control six or more lands.
Exile a planeswalker card you own from outside the game. You may cast that card this turn.

Menace
Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{3}{R}: Another target creature you control gains menace until end of turn.

Trample
Whenever you cast a noncreature spell, crystallize. If you create a Treasure this way, Heartforge Savant deals 1 damage to you for each Treasure you've created this turn. (Put a +1/+1 counter on a creature you control or create a Treasure.)

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{X}{R}: Hearth Dweller gets +X/+0 until end of turn.

Target permanent you control gains hexproof until end of turn. If that permanent is a creature, it also gets +1/+1 until end of turn.

If one or more counters would be put on a creature you control, that many plus one of each of those kinds of counters are put on that permanent instead.

Creature spells you cast cost {1} less to cast.

Reach

Haste
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Ship Vehicle becomes an artifact creature until end of turn.)

Put a +1/+1 counter on up to one target creature. Untap it. You gain 3 life.

Heat Blast deals X damage to target creature or planeswalker.

Heat Ray deals X damage to target creature.

Whenever a creature blocks, Heat of Battle deals 1 damage to that creature's controller.

Until end of turn, gain control of target creature and it gains haste and shimmer. Untap it. (Whenever it attacks this turn, create a tapped and attacking token that's a copy of it. Exile that token at the beginning of the end step.)

Heated Dispute deals 3 damage to any target.
Ferocious — This spell costs {2} less to cast if you control a creature with power 4 or greater.

Shuffle your library, then reveal cards from the top of your library until you reveal a creature card. Put that card onto the battlefield and the rest on the bottom of your library in a random order. Heathen Rise deals damage to you equal to the number of cards revealed this way.
Ferocious — That creature gains haste if it has power 4 or greater.