msem-instigator

Whenever a nontoken creature you control dies, create a 1/1 black Worm creature token.
Sacrifice Fertile Grave: Create a 1/1 black Worm creature token.

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Kindle 2—{2}{G} ({2}{G}, Exile this card from your graveyard: Create two 1/1 colorless Elemental creature tokens. Kindle only as a sorcery.)

Target creature you control gets +3/+0 until end of turn. Other creatures you control get +1/+0 until end of turn.

Menace
When Fervent Devout enters, choose one —
• Put a +1/+1 counter on Fervent Devout.
• Create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
Whenever Fervent Ensign attacks, add {R} at the beginning of your next main phase.

Target creature gets +1/+0 and gains first strike and haste until end of turn.

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

When Festering Waif enters, each opponent mills two cards.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

When Festival Celebrants enters, put a +1/+1 counter on each creature you control.

Inspired — Whenever Festival Decorator becomes untapped, draw a card.

When Festival Rioters enters, create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”
{1}{R}: Festival Rioters gets +2/+0 until end of turn.

Choose one —
• Festival Sabotage deals 2 damage to any target.
• Audition for red. (Create a 1/1 Construct Actor creature token, a Warrior Role giving 3/2 and trample, or a Wizard Role giving 2/2 and prowess. Roles replace older ones.)

Destroy target enchantment and all other enchantments with the same name as that enchantment.
Draw a card.

Destroy target artifact and all other artifacts with the same name as that artifact.
Draw a card.

Target creature and all other creatures with the same name as that creature get +2/+2 until end of turn.
Draw a card.

Return target nonland permanent and all other permanents with the same name as that permanent to their owners' hands.
Draw a card.

Choose one —
• Target attacking creature gets +2/+2 until end of turn.
• Destroy target artifact.

Festive Servitor gets +1/+1 for each color among spells you've cast this turn.
{2}: Add one mana of any color.

{B}: Fetid Nibbler gains deathtouch until end of turn.

When Feverish Noble dies, you draw two cards and you lose 2 life.

Whenever Fickle Feeder blocks, fateseal 1. (To fateseal 1, look at the top card of an opponent's library, then you may put it on the bottom of that player's library.)

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Fickleflame Summon enters or leaves the battlefield, draw a card, then discard a card.

Whenever Field Chaplain perseveres, you gain 3 life. (A creature perseveres when it survives damage.)

At the beginning of combat on your turn, you may have target artifact you control become a 3/3 artifact creature until end of turn. If you do, it and Field Engineer attack this turn if able.

Fiendish Yaoguai can't block.
Scavenge {5}{B} ({5}{B}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)