msem-instigator

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.)

Deathtouch
Discard a card: Headless Carriage gains indestructible until end of turn. Tap it.
Ride {2}{B}{B} ({2}{B}{B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Flying
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

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 {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.

Gain control of target attacking creature until end of turn. Untap it. It gains indestructible until end of turn.

Flying, vigilance, deathtouch, lifelink

At the beginning of your upkeep, if you have less life than an opponent, you lose 1 life and you draw a card.

Deathtouch
Whenever another creature dies, its controller discards a card at random.

Augmented — Whenever you cast a spell from your hand, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, exile cards from the top of your library until you reveal a nonland card with mana value less than that spell's mana value. You may cast that card without paying its mana cost. Put the revealed cards not cast this way on the bottom of your library in a random order.

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

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.

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, lifelink

Choose a nonland permanent type. Destroy all permanents of the chosen type. Each player who controlled a permanent destroyed this way draws a card.

{2}{G}: Exile up to three cards from graveyards. Autocrat X, where X is the number of cards exiled this way. (If you don't control an autocrat, put X +1/+1 counters on this. It becomes an autocrat until it has no +1/+1 counters on it.)
Whenever Hegemony Monarch attacks, you may exile target card from a graveyard. If you do, untap it and it gains trample until end of turn.

Whenever you cast a spell with two or more black mana symbols in its mana cost, you draw a card and you lose 1 life.

Disgraced 5 (This enters with five -1/-1 counters. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
Prevent all combat damage that would be dealt to Heir Unapparent.

{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.”)

Colossal 5—{8}{W}{W} (You may cast this for its colossal cost to have it enter with five +1/+1 counters; or pay {8}{W}{W} as a sorcery: Put five +1/+1 counters on it if it has none.)
Ward {5}
When Hekaton Dismantler's colossal ability puts one or more counters on it, tap each creature you don't control. Those creatures don't untap during their controller's next 100 untap steps.

Flying
When Helar Ritualist enters or whenever you cast a spell, if {W}{B} was spent to cast it, each opponent loses 3 life and you gain 3 life. Put a +1/+1 counter on Helar Ritualist.

Flying, lifelink
When Helar's Herald dies, target opponent may give themselves two poison counters. If they do, return Helar's Herald to its owner's hand. Otherwise, return Helar's Herald to the battlefield tapped under its owner's control.

Tithe (As you cast this spell, you may tap three artifacts and/or creatures you control.)
Creatures you control gain indestructible until end of turn. If this spell's tithe was paid, put a +1/+1 counter on each creature you control.