msem-instigator

When Greypelt Clergy enters, choose one —
• Put a +1/+1 counter on Greypelt Clergy.
• Permutate. (You may remove a counter from a creature you control. If you do, put two +1/+1 counters on a different creature you control.)

Whenever another Hound you control enters, put a +1/+1 counter on Greypelt Initiate.

Trample
Greypelt Ruffian gets +1/+1 as long as you control a storied permanent. (Enchantments and legendary permanents are storied.)

Flying, lifelink

{B}, {T}, Exile two cards from your graveyard: Create a 1/1 white Spirit creature token with flying.

First strike
Whenever Guardian of the Eclipse attacks, you may exile another target attacking creature you control, then return it to the battlefield under your control tapped and attacking.

When Guardian of the Wurm enters, create a 6/6 green Wurm creature token with trample.

Flash
When Guppyfin Duelist enters, create a green Aura enchantment token named Piranha's Prowess attached to target creature. The token has enchant creature and “Enchanted creature gets +2/+2.” Untap that creature.

When Gusma's Artisan enters, search your library for a card, then shuffle and put that card on the bottom of it.
{2}{U}, Sacrifice Gusma's Artisan: Manifest the bottom card of your library. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Prowess
Gusma's Emissary gets +1/+1 as long as you control a black or green permanent.

When Gyreon Pickpocket enters, target opponent discards a card. If a land card was discarded this way, draw a card.

Whenever Hadik's Striker is dealt damage, you gain that much life.

Haste
{2}{W}, {T}: Hair-Trigger Marshall deals 2 damage to target blocking creature.

Heroic — Whenever you cast a spell that targets Halcyon Hoplite, Halcyon Hoplite gains flying until end of turn.
When Halcyon Hoplite dies, if it was enchanted, create a 1/1 white Bird creature token with flying.

Lifelink
Whenever you cast a spell with mana value 2 or less, put a +1/+1 counter on Hallowed Moon Sentinel.

When Hamlet Bounder enters, choose one —
• Destroy target artifact or enchantment.
• Create a 1/1 white Peasant creature token.

You don't lose unspent mana as steps and phases end except at end of turn.
Hand of the Chroma gets +1/+1 for each color of unspent mana you have.

Rhapsody {4}{R}{R} (Pay {4}{R}{R} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Menace

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)
Whenever Haploc Striker attacks and isn't blocked, you may cast target instant or sorcery card from your graveyard if its mana value is less than or equal to Haploc Striker's power. Exile that card instead of putting it into your graveyard as it resolves.

Flying, trample
Harbinger of Falling Skies enters with X +1/+1 counters on it.
Whenever Harbinger of Falling Skies attacks, you may remove a +1/+1 counter from it. If you do, draw a card.

When Harbinger of Growth enters, create a 1/1 green Saproling creature token.
{1}{G}, Sacrifice Harbinger of Growth: Populate. (Create a token that's a copy of a creature token you control.)

Flying
Assault {2}{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 Harbinger of Locusts assaults, you may search your library for an Insect card, reveal it, put it into your hand, then shuffle.

When Hardened Explorer enters, choose one —
• Destroy target artifact.
• Put a +1/+1 counter on Hardened Explorer. It gains haste.

When Hardlight Visionary enters, create a Function token with “Until end of turn, target creature becomes a 5/5 Dragon and gains flying.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Whenever you cast an enchantment spell, you may pay {W}. If you do, put a +1/+1 counter on target creature.