msem-instigator

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

{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.

({T}: Add {G} or {W}.)
Heart of the Glade enters tapped unless you control a basic Forest or a basic Plains.

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.

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.

Flying, vigilance, deathtouch, lifelink

Enchant creature
When Heartstrings leaves the battlefield, exile enchanted creature.
Whenever enchanted creature attacks or blocks, exile it at end of combat.

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.

At the beginning of your upkeep, if each opponent controls more lands than you, search your library for a basic land card, reveal it, and put it into your hand, then shuffle.

Flying
{T}, Tap another untapped creature in Heaven's Gale Harrier's pack: Tap target creature. (Two or more creatures you control with equal power are in a pack.)

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
Whenever this creature attacks, if it's merged with another card or token, it deals 2 damage to target player or planeswalker.

{T}: Add {C}.
When Heavenly Temple enters, target creature gains flying until end of turn.
{2}: Return Heavenly Temple from the battlefield to its owner's hand.

Enchant creature
Enchanted creature has flying and can only block creatures with flying.

{1}, {T}: Add one mana of any color.
{1}, {T}, Sacrifice Heavy Moneybag: Post a bounty on target creature or planeswalker. Activate only as a sorcery. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

Whenever Hedge Dashers attacks, if you control a permanent with a counter on it, Hedge Dashers gets +1/+1 and gains trample until end of turn.

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

Rogues and Pirates you control have haste.
Whenever one or more creatures you control deal combat damage to a player, exile the top card of your library. You may play that card this turn.

Untap target creature. It gets +1/+3 until end of turn.

Hellfire Caverns enters tapped.
{T}: Add {R}.
{2}{R}: Until end of turn, Hellfire Caverns becomes a 3/3 Devil creature with menace. Activate only if you're horrific.

Hellfire Crater enters tapped. When it enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {B} or {R}.

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

Equipped creature has “{T}: Target attacking creature gets +1/+1 until end of turn.”
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)