msem-instigator

Flying
Whenever Haunting Horseman deals combat damage to a player, that player discards a card.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Flying
{2}{W}: Prevent all damage that would be dealt to and dealt by creatures with counters on them this turn.

Lifelink, haste
At the beginning of your end step, Fae-Frill Fox deals X damage to target player, where X is the number of times you gained life this turn.

Ophan Titan gets +3/+3 as long as there are no nonland cards in your graveyard.
Morph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

When Etched Longspear enters, attach it to target creature you control.
Equipped creature gets +2/+0.
Equip {3}

Flying, first strike, vigilance, lifelink
When Bastion Valkyrie dies, create three Function tokens with “Choose a creature targeted by this spell. It gains flying, first strike, vigilance, and lifelink until end of turn.” (They're enchantments. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Whenever a Plains you control enters, you may put a creature card with mana value 2 or less from your hand onto the battlefield.

If a player would gain life, that player adds that much {C} instead.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
Other creatures you control with distorted get +2/+2.

Whenever Ontarachie Hunter attacks, each opponent loses 1 life.
At the beginning of your end step, if an opponent has 10 or less life, transform Ontarachie Hunter.

Whenever you cast a spell, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Gilded Duo gets +2/+0 until end of turn.

Choose a nonlegendary, nonland card name. Target opponent reveals their hand and discards a card with that name.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Menace
Each opponent's maximum hand size is reduced by the number of counters on Fahrib's Lieutenant.
Whenever an opponent discards a card, put a +1/+1 counter on Fahrib's Lieutenant.

Whenever a player casts a noncreature spell, create a 1/1 white Human Soldier creature token.
{1}{U}, Tap four untapped creatures you control: Counter target noncreature spell.

Gleaming Hot Springs enters tapped unless you control a Mountain.
{T}: Add {W} or {U}.

Target opponent reveals their hand. You choose a creature card from it. That player discards that card.

Flash
First strike
If you cast Taiyohata Champion during your declare attackers step, it enters tapped and attacking.

Create X 1/1 white Soldier creature tokens, where X is the number of creatures you don't control.

This spell costs {2} more to cast for each target beyond the first.
Choose one or more —
• Remove all counters from target non-Gorgon creature. If it has toughness 2 or less, destroy it.
• Return target creature or planeswalker card from your graveyard to your hand. You gain 4 life.
• Exile target player's graveyard.

Draw two cards.
Flashback—{2}{U}, Discard a card. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Whenever you cast a noncreature spell, Shiverpass Taskmage explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)

Firebolt deals 2 damage to any target.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

First strike, vigilance

Flying
When Imperator Namuzzar enters, search your library for an artifact or enchantment card, reveal it, put it into your hand, then shuffle.
Civilized — Lammasu you control get +2/+2 and have hexproof as long as you control an artifact, a creature, and an enchantment.

Create a 2/2 colorless Spirit creature token.
When inscribed creature dies, create a 2/2 colorless Spirit creature token.
Inscribe {2}{B}{B} ({2}{B}{B}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)