msem-instigator

Haste
Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)

Enchant opponent
When Ranidaphobia enters, create a 1/1 blue Frog creature token.
Creatures enchanted player controls can't block Frogs.

Enchant creature you control
When Rapacious Instinct enters, enchanted creature deals damage equal to its power to target creature you don't control.
Enchanted creature gets +1/+0.

Choose a Function added to Rapid Recursion. Create a Function token with those effects. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)
Draw a card.

Untap target creature. It gets +2/+2 and gains reach until end of turn.
Monument {3}{G} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

Target creature can't be blocked this turn. It 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 that creature, then you may put that card in your graveyard.)

Menace
Discard a card: Target artifact creature you control salvages Rappel Liner. Activate only if Rappel Liner is in your graveyard and only as a sorcery. (Exile this card until that creature leaves the battlefield. When that creature deals combat damage to a player, return a card it salvaged to your hand.)

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)

When Rat King enters, create two 1/1 black Rat creature tokens with “This creature can't block.”
Whenever Rat King or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Rattlecage Terror enters tapped.
{1}{B}: Return Rattlecage Terror from your graveyard to your hand. When you do, another target creature card with mana value 3 or less in your graveyard gains this activated ability until end of turn, except it costs {1} more to activate.

Menace
When Rattled Bones dies, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Choose one or both —
• Each player sacrifices an artifact.
• Each player sacrifices an enchantment.

Enchant creature
When Ravage of Moments enters and at the beginning of your upkeep, put a -1/-1 counter on enchanted creature.

Ravaged Monument enters tapped.
{T}: Add {G}.
{2/G}{2/G}: Ravaged Monument becomes a 4/4 green Elemental creature until end of turn. It's still a land.

Whenever a creature you control dies, each opponent discards a card.
Revive {6}{B} ({6}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Equipped creature is a Flagbearer in addition to its other types.
While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least one Flagbearer on the battlefield if able.
Equip {5}

Reach, deathtouch
Whenever you cast a spell from your graveyard, you may have Raven-Cursed Dominik fight target creature.

Whenever Ravencaller or another creature enters from your graveyard, create a 1/1 blue Bird creature token with flying.

Whenever one or more other creatures you control deal combat damage to an opponent, choose one —
• That player discards a card at random.
• That player sacrifices a creature with toughness 4 or less.

When Ravenous Abomination enters, choose one —
• Create two Treasure tokens.
• Put a +1/+1 counter on Ravenous Abomination.

Ravenous Attraction enters with a +1/+1 counter on it.
Whenever a creature you control dies, double the number of each kind of counter on Ravenous Attraction.

The second spell you cast each turn costs {2} less to cast.
Whenever you cast a spell, each opponent loses 1 life and you gain 1 life.

First strike, trample
Whenever a creature dealt combat damage by Ravenous Forsaken this turn dies, put a +1/+1 counter on Ravenous Forsaken.
{2}{R}: Ravenous Forsaken gets +3/+0 until end of turn.

Ravenous Grue enters with a menace counter on it.
{5}{B}{B}, Remove a menace counter from Ravenous Grue: Destroy target creature.

Ravenous Hollow enters tapped.
{T}: Add {B} or {R}.
{2}{B}{R}: Until end of turn, Ravenous Hollow becomes a Wolf creature with first strike in addition to its other types.
Scavenge {2}{B}{R}