msem-instigator

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Flame-Tailed Lizard has three or more +1/+1 counters on it, remove them all and transform it.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever Flamecloaked Artisan attacks, exile the top card of your library. If it's a nonland card with mana value less than Flamecloaked Artisan's power, you may cast it this turn, and you may cast it as though it had flash.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever a +1/+1 counter is put on Flamerider, you may have it deal damage equal to its power to target creature.

Haste
Whenever Flamewake Elk attacks, you may put a +1/+1 counter on another target attacking creature.

You may exert Fleetfooted Survivalist as it attacks. (An exerted creature won't untap during your next untap step.)
Whenever an exerted creature you control deals combat damage to a player, draw a card.

Flying
When Fleeting Distractor enters, sacrifice it unless you return another creature you control to its owner's hand.

Breach (Whenever this deals combat damage to a player, you may have it become an Aura Curse until your next turn. Attach it to that player.)
Once each turn, when a Curse you control becomes attached to an opponent, you may sacrifice it. If you do, reveal cards from the top of your library until you reveal a Curse card. Put that card onto the battlefield attached to that player, and the rest on the bottom of your library in a random order.

Whenever you cast a black spell, put a +1/+1 counter on Flenser's Lieutenant.
{B}{B}: Return Flenser's Lieutenant from your graveyard to your hand.

Menace
Whenever an opponent activates an ability that isn't a mana ability, Flensing Tormentor deals 1 damage to that player.

{3}{B}: Regenerate Flesh Hoarder Ghoul. (The next time this creature would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)

Fleshcrawler gets +1/+0 for each player that has lost life this turn.

Deathtouch
When Flesheater Vine enters, you may have it consume. If you do, put a +1/+1 counter on it and you gain 3 life. (To consume, sacrifice another creature or exile a creature card from your graveyard.)

{1}{B}, Discard a creature card: Draw a card.
{1}{B}, {T}, Exile a creature card from your graveyard: Create a tapped 2/2 black Zombie creature token.

Whenever Fleshwarper or another Horror you control dies, each opponent loses 1 life and you gain 1 life. You may mill a card.

Lifelink
Pay 3 life: Flightful Fledgling gains flying until end of turn.

Whenever another creature you control enters, Flightpath Trainee gains flying until end of turn.

Flying
Menagerie — At the beginning of combat on your turn, if there are five or more creature types among creatures you control, create a 1/1 black Insect Spirit creature token with flying and you gain 1 life.

Whenever an Aura you control enters, draw a card.

At the beginning of your upkeep, if you have more life than an opponent, create a 1/1 black Insect Spirit creature token with flying.
{3}{B}: Each opponent loses X life and you gain X life, where X is the number of Clerics you control.

Flying
Whenever Flying Scorpion attacks, it gets +1/+0 until end of turn for each creature you control that's not attacking.

Noncreature spells you cast cost {1} more to cast.
Noncreature spells your opponents cast cost {1} more to cast unless that player controls more creatures than you.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
{U}{R}, Exile an instant or sorcery card from your graveyard: Foolhardy Huo gains flying and first strike until end of turn.

When Forest Whale dies, put a number of +1/+1 counters on target creature you control equal to Forest Whale's power.

Heroic — Whenever you cast a spell that targets Forge Adept, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
{6}{R}: Create a 3/3 colorless Golem enchantment artifact creature token. If mana from an artifact was spent to activate this ability, that token gains haste.

Attacking creatures you control have “{R}: This creature gets +1/+0 until end of turn.”
Armed — Whenever Forgeborn Barbarian attacks, add {R} for each equipped creature you control.