msem-instigator

When Heirloom Seeker enters, you may search your library for an Equipment card, reveal it, then shuffle and put that card on top of it.
Heirloom Seeker has first strike as long as it's equipped.

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.

At the beginning of each combat, up to one target creature can't attack or block this turn.

Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)
Other creatures you control have infiltrate.

When Helicos Aberration enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Flying, lifelink, haste
At the beginning of the end step, sacrifice Helix Entity.

This spell costs {X} less to cast, where X is your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)
Trample

Menace
{1}{B}{R}: Creatures you control get +1/+0 until end of turn.

When Hellion Devastator enters, destroy up to one target nonland permanent with mana value 3 or less.
Cycling {2} ({2}, Discard this card: Draw a card.)

Haste
The first instant or sorcery spell you cast each turn costs {1} less to cast.
{R}, {T}, Sacrifice Hellspark Prankster: Change the target of target spell with a single target.

Lifelink

Whenever you cast a legendary spell or play a legendary land, put a +1/+1 counter on Henros, Royal Herald and you gain 1 life.
{2}{W}: Look at the top six cards of your library. You may exile a legendary card from among them. Then shuffle. If the exiled card has mana value less than Henros's power, you may put it onto the battlefield tapped. If you don't, put it into your hand.

This spell can't be countered.
Vigilance
Noncreature spells cost {1} more to cast.

Pressure {2}{B} (You may cast this spell for its pressure cost if there are seven or more cards in your graveyard.)
Menace (This creature can't be blocked except by two or more creatures.)

When Herald of Darkness enters, destroy up to one target creature with mana value 3 or less.

Lands you control are colorless lands named Wastes with “{T}: Add {C}” and lose all other card types and abilities.

Flying, haste
Whenever you attack with three or more creatures, harmonize three times. (To harmonize, trigger up to one harmony of a permanent you control.)
If you would harmonize, you may instead return Herald of Festivities from your graveyard to your hand.

Rapport — Whenever Herald of the Hunt and at least one other creature you control become tapped, nourish 1. (To nourish 1, either put a +1/+1 counter on this creature or create a 1/1 white Citizen creature token.)

Herald of the Yaoguai has indestructible as long as two or more creatures you control entered this turn.

{B}{R}, {T}, Sacrifice Heretical Soulshifter: Return target creature card from your graveyard to the battlefield. It gains haste until end of turn. Activate only as a sorcery.

You may have Hero of Shengin Province assign its combat damage as though it weren't blocked.
{2}{G}: Until end of turn, you may have creatures you control assign combat damage as though they weren't blocked. Activate only if Hero of Shengin Province is in your graveyard.

Whenever Heroic Exemplar attacks, if its power is greater than its base power, other creatures you control get +1/+1 until end of turn.

Prowess
Whenever Hethwyr Warcaster or another Wizard you control enters, you may draw a card.

Flash
When Hexfang Ascetic enters, return target spell to its owner's hand.

As Hexplate Companion enters, choose a card name.
You and Hexplate Companion each have protection from the chosen card name.