msem-instigator

Haste
Herald of Unity's power is equal to the number of creatures you control.

Flying, prowess
Whenever one or more creatures attack, you gain life equal to the greatest power among those creatures.
Whenever you cast a white spell, you may have Heraldry become an Angel creature in addition to its other types or stop being a creature.

Beckon Ox {1}{W} ({1}{W}: This enchantment permanently becomes an Ox creature in addition to its other types.)
Vigilance
Whenever a creature or another enchantment you control enters, you gain 1 life.

Hexproof, vigilance, lifelink

Deathtouch
Whenever a storied permanent you control enters, remove up to two counters from target creature or planeswalker an opponent controls. (Enchantments and legendary permanents are storied.)

Whenever Hero's Henchman attacks, another target creature you control gets +1/+1 until end of turn.

Colossal 2—{6}{W}{W} (You may cast this for its colossal cost to have it enter with two +1/+1 counters; or pay {6}{W}{W} as a sorcery: Put two +1/+1 counters on it if it has none.)
When Heroes' Adversary's colossal ability puts one or more counters on it, exile target creature an opponent controls until Heroes' Adversary leaves the battlefield.

Lifelink
Tap three other untapped creatures and/or artifacts you control: Transform Heroic Crusader.

First strike, lifelink
Once each turn, when another nontoken creature you control dies, you may create a 2/2 white Elk Spirit creature token with first strike and lifelink named Fawn of Hesediel.

When Hex Maniac enters, return target non-Human creature card from your graveyard to your hand.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, you gain life equal to its mana value.

Lifelink
Triggered abilities of creatures you control that would trigger only when that creature enters instead trigger whenever you gain life for the first time each turn.

Whenever High-Priestess Nebti attacks or blocks, create a 2/2 white Cat creature token.
{1}{R}{R}, Tap an untapped Cat creature you control: That creature fights target creature you don't control.

{T}: Add {G}.
Dominance — {T}: Add {G}{G}. Activate only if you control the creature with the greatest power or tied for the greatest power.

Whenever Highpeak Rider attacks, search your library for a land card and put it onto the battlefield, then shuffle. Sacrifice that land at the beginning of the next end step.

Flying
You may look at the top card of your library any time.

Assault {B} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Hilaback Outriders assaults, it gains menace until end of turn.

When Hired Kalak enters, put target card from your graveyard on top of your library.

Civilized — As long as you control an artifact, a creature, and an enchantment, prevent all combat damage that would be dealt to Hirsute Champion.

At the beginning of your upkeep, each opponent mills cards equal to the number of card types among permanents you control.

First mate—Each nonland card in your starting deck has the same name as exactly one other card in your starting deck. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Vigilance
Whenever you cast a spell with the same name as a card in your graveyard, draw a card.

Hollow Queen can't be blocked by tokens.
Whenever Hollow Queen deals combat damage to a player or planeswalker, you may remove a counter from a permanent you control. If you do, put a +1/+1 counter on target creature you control.

While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least one Flagbearer on the battlefield if able.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

When Honored Retinue enters, choose a creature you control. You may search your library for a creature card with the same name as that creature, reveal it, put it into your hand, then shuffle.

When Hooded Inquirers enters, draw two cards.