msem-instigator

{1}, {T}, Move a -1/-1 counter from another creature onto Fervent Arbiter: Exile target creature you don't control until Fervent Arbiter leaves the battlefield.

At the beginning of your upkeep, exile the top card of your library. Until end of turn, you may play that card if it's an instant or sorcery card.

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.”

Flying
You may exert Fervent Igmel as it attacks. When you do, add {R}{R}{R}{R}. Until end of turn, you don't lose this mana as steps and phases end. (An exerted creature won't untap during your next untap step.)

Attacking creatures you control get +1/+0.

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

{2}{R}{R}, Exile an instant or sorcery card from your graveyard: Fervid Dragonheart gets +1/+2, gains flying, and becomes a Dragon until end of turn.

Whenever a creature you control dies, put a rot counter on Fester Swarm and you gain 1 life.
{B}{G}, Remove two or more rot counters from Fester Swarm: Create a 1/1 green Insect creature token, then put a +1/+1 counter on it for each rot counter removed this way.

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

When Festering Shipwreck enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
At the beginning of each player's upkeep, that player sacrifices a nonland permanent.

At the beginning of your upkeep, mill a card.
{1}, Exile three cards from your graveyard: Put a -1/-1 counter on target creature.

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.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{T}: Add {C}. If you're in a renaissance, add one mana of any color instead.
{3}, {T}: Scry 1.

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.)

Harmony — Create a 1/1 white Bird creature token with flying.
{4}: Harmonize. (Trigger up to one harmony of one permanent you control.)

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.

Enchant creature you control
When Festive Euphoria enters, you gain life and draw cards equal to enchanted creature's power.
Enchanted creature can't be blocked by creatures with power 2 or less.

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