msem-instigator

Whenever another nonland creature you control dies, return it to the battlefield tapped with a sapling counter on it. It becomes an Animus land named Bitter Hazel, loses all other card types, and gains “{T}: Add {G}” and “Pay this card's mana cost: This land becomes a creature until end of turn. It's still a land.”

{4}{G}{G}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.)
When Grizzly Matriarch becomes monstrous, destroy target noncreature permanent an opponent controls.

Archive 6
Grohl's Study's power and toughness are each equal to the number of cards in the archived library.
Whenever Grohl's Study deals combat damage to a player, you may put a card from the archived library into your hand.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Sacrifice another creature: Grotesque Defiler gains flying until end of turn.
Whenever Grotesque Defiler deals combat damage to a player, if you're in a renaissance, that player discards a card.

Menagerie — When Grotto Guardian enters, if there are five or more creature types among creatures you control, target creature you don't control gets -2/-2 until end of turn.

When Grotto Scarab enters, create two 1/1 green Insect creature tokens for each creature you controlled that died this turn.

Other creatures you control that are Knights or have Adventures get +1/+1.

Menace
Death knell — Put a +1/+1 counter on Guiltless Wraith. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

Whenever H.S.S. Demeter becomes blocked by a creature, gain control of that creature.
Whenever H.S.S. Demeter deals combat damage to a player, draw two cards.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Flash
Flying
Whenever H13 Wasp enters or you cast an another spell with flash or an instant, exile up to one target nonland permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

[+1]: Haide Bankbuster deals 2 damage divided as you choose among one or two targets.
[+1]: Draw two cards unless any player has Haide Bankbuster deal 3 damage to them.
[–9]: Until end of turn, gain control of all permanents target player controls and they gain haste. Untap those permanents.

Flying
When Hallowed Executioner enters, it deals 2 damage to each creature without flying.

Enchant land
Enchanted land has “{T}: Tap target creature.”

Hexproof
Deploy 4 (As this enters, you may tap any number of other creatures you control with total power 4 or more.)
When Hamlet Witch enters deployed, return target card from your graveyard to your hand.

When Hand of the Evil One enters, mill three cards. Draw a card for each Zombie card milled this way.
Unearth abilities you activate cost up to {1} less to activate.

Flying
Whenever Hao'Tai deals combat damage to a player, that player exiles the top five cards of their library and separates them into two piles. Put an ember counter on each card in the pile of your choice. You may play cards from exile with ember counters for as long as they remain exiled.

Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle. Put a +1/+1 counter on each creature you control.

Harpoon Launching deals 3 damage to any target. Create a 1/1 red Goblin creature token.

When Harshapal Banner enters, create three 1/1 white Soldier creature tokens with vigilance.
Equipped creature gets +2/+2.
Equip {3}

Whenever you cast an instant or sorcery spell from your hand, put that card onto the battlefield face down as a 2/2 creature instead of putting it into your graveyard as it resolves.
Whenever a face-down creature you control deals combat damage to an opponent, you may exile it. If you do, you may cast it without paying its mana cost.

Each player discards their hand, then draws cards equal to the greatest number of cards discarded this way.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever another noncreature source deals damage to a creature or player, you may have Hav'za, Itavan Warchief deal half that damage, rounded up, to any target.

Menace
At the beginning of your end step, He of All Hallow's Eve deals damage equal to its power to you unless you're horrific. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Flying
When Heartless Host enters, arm target creature. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)