When Graverot Soothsayer enters the battlefield, you may sacrifice another creature. If you do, return that card from your graveyard to the battlefield under your control at the beginning of the next end step.

When Gray Merchant of Asphodel enters the battlefield, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way.

When Grovelit Meditation enters the battlefield, you gain 4 life.
{1}{G}, Sacrifice Grovelit Meditation: Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

When Hans Nehmann enters the battlefield, you may search your library for a card named Marie Laurent or Diago Maldovo and reveal that card. If you do, shuffle, then put the card on top of it.
Legendary Allies you control have lifelink.

When Hardlight Hedron enters the battlefield, draw two cards, then discard a card.
{U}, {T}, Sacrifice Hardlight Hedron: Scry 2.

Vigilance
When Hardlight Paragon enters the battlefield, distribute two +1/+1 counters among one or two target creatures.

When Harvesting Blade enters the battlefield, target opponent exiles two cards from their hand.
Equipped creature gets +2/+1 and has “When this creature dies, you may cast a card exiled with Harvesting Blade with equal or lesser mana value without paying its mana cost.”
Equip {3}

Flash
When Hazard Blade enters the battlefield, destroy target creature an opponent controls that was dealt damage this turn.
Equipped creature get +4/+0.
Equip {5}

Defender
When Herald of Awakening enters the battlefield, draw a card. Then discard a card unless you control a Ruin.
Whenever a Ruin you control becomes spellcharged, Herald of Awakening loses defender until end of turn.

This spell costs {1} less to cast for each instant and/or sorcery card in your graveyard.
When Heretic Hunters enters the battlefield, you may discard your hand. If you do, draw a card and Heretic Hunters deals 2 damage to each opponent.

Flying
When Hoarding Rocs enters the battlefield, look at the top three cards of your library. You may reveal an artifact card from among them and put it into your hand. Put the rest on the bottom in a random order.

When Humble Barkeep enters the battlefield, create a Food token.
Whenever you sacrifice a Food, put a +1/+1 counter on Humble Barkeep.

Trample
When Hunger's Door enters the battlefield, you may return target Aura card from your graveyard to the battlefield attached to Hunger's Door.

Trample, haste
When Impetuous Knight enters the battlefield, target opponent creates a Windmill artifact token with “{T}: Prevent all combat damage target Knight would deal to you this turn”.
Impetuous Knight attacks each combat if able as long as an opponent controls a Windmill.

When Impetuous Underling enters the battlefield, you may search your library for a card and put it into your graveyard, then shuffle.

When Indentured Labourer enters the battlefield, you draw a card and lose 1 life.

Vigilance
When Indomitable Jicru enters the battlefield, you gain 5 life and draw a card. If it wandered, creatures you control get +2/+2 until end of turn.
Wander {6}{G}{W}

When Inside Job enters the battlefield, target creature can't be blocked this turn.
Whenever you amp it up, return Inside Job to its owner's hand.

When Insight Insignia enters the battlefield, you may attach it to target creature you control.
Whenever equipped creature deals combat damage to a player, surveil 1, then draw a card.
Equip {U}

When Kakomanties Circle enters the battlefield, create a 2/2 black Zombie creature token.
Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.

Enchantment spells you cast cost {1} less to cast.
When Keeper of Starlight enters the battlefield, reveal the top five cards of your library. You may put an enchantment card from among them into your hand. Put the rest on the bottom of your library in any order.

Flash
When Klemnae Rescuer enters the battlefield, you may return a permanent you control to its owner's hand.

When Kywon's Breathtaker enters the battlefield, you may exile a creature card from your graveyard. When you do, target creature gets -3/-3 until end of turn.

Flying
When Kywon's Skyhunter enters the battlefield, draw a card.

Enchant creature
When Left to the Sea enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.