msem-instigator

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Fox of a Radiant Meadow has double strike as long as you're in a renaissance.

Whenever Fox of the Mushroom Forest enters or deals combat damage to a player, its activated abilities cost {W} less to activate until your next turn.
{W}, Sacrifice Fox of the Mushroom Forest: Counter target noncreature spell unless its controller pays {2}.

Whenever Fox of the River Run attacks, if you control a creature with power 4 or greater, you may discard a card. If you do, draw a card.

When Frantic Efreetspeaker enters, you may discard a card. If you do, draw a card.
{2}, Exile Frantic Efreetspeaker from your graveyard: Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

First strike
Stampede — Whenever Frenzied Nacatl and a creature with greater power attack, Frenzied Nacatl gets +2/+0 until end of turn.

Whenever you sacrifice another permanent, Fretport Mob gets +1/+1 and gains haste until end of turn.

Friend of the Woods has hexproof as long as it has a +1/+1 counter on it.
{1}{G}, {T}: Put a +1/+1 counter on Friend of the Woods.

Whenever a creature an opponent controls deals damage to you, monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)
Frigid Behemoth can't attack unless it's monstrous.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, Frilled Drakeling gains menace until end of turn.

Vigilance
Warriors you control have ward {X}, where X is the number of Warriors you control. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {X}.)

Frondpond Prankster can't be blocked.
Whenever Frondpond Prankster enters or deals combat damage to a player, target player reveals their hand, then you choose any number of nonland cards from it. That player puts those cards on the bottom of their library in a random order, then draws that many cards.

Trample

When Frontier Savior enters, return up to two target creature cards with mana value 3 or less from your graveyard to the battlefield.

Improve {G} ({G}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
When Frontier Trackers dies, create a 1/1 green Elf creature token.

Improve {W} ({W}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever Frontier Wayfinder attacks, untap each other creature you control.

Flying
This spell can't be countered.
When Frostbreath Dragon enters, tap target creature. It doesn't untap during its controller's next untap step.
Whenever Frostbreath Dragon becomes the target of a spell or ability, counter it unless its controller pays {2} and discards a card.

Deathtouch
{B}{G}, Exile Frosted Adder from your graveyard: Return another target creature card from your graveyard to your hand.

At the beginning of your upkeep, mill a card.
Whenever you cast a spell from your graveyard, create a 2/2 green Wolf creature token.

If a source you control would deal noncombat damage, it deals double that damage instead.

{7}{R}: Up to three target creatures you control get +3/+0 and gain menace until end of turn. This ability costs {2} less to activate if you control a legendary creature.

Flying
Whenever a player casts a spell, if it isn't that player's main phase, each of their opponents may draw a card.

When Gallipot Apothecary enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

{T}: Surveil 1.
Crew 2
Whenever one or more cards leaves your graveyard, this artifact becomes an artifact creature until end of turn.

When Gamhaugen Stablehand enters, put a +1/+1 counter on target creature you control. You gain 1 life.

As long as you control five or more creatures, if you would create a token, you may instead create Hu Li, a legendary 4/4 white Fox Spirit creature token with flying and lifelink.