msem-instigator

Destroy target attacking or blocking creature.
Bulwark — This spell costs {1} less to cast if you control a creature with toughness 4 or greater.

Trample
When Rallios's Champion enters, look at the top six cards of your library. You may put a Warrior card with lesser mana value from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
Other Warriors you control get +1/+1.

Create three 1/1 white Soldier creature tokens. If you control an attacking creature, they're tapped and attacking. If you control a blocking creature, they're blocking target attacking creature.
Quickdraw {2}{W} (When a creature you control blocks or becomes blocked, you may cast this for {2}{W}.)

Whenever Rambunctious Upstart attacks, up to one target creature gets -3/-1 until end of turn and up to one target creature gets +3/+1 until end of turn.

Flash
Voracious 2 (As this enters, you may sacrifice up to two artifacts and/or creatures. This creature enters with that many +1/+1 counters on it.)

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.

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

When Ravenous Chupacabra enters, destroy target creature an opponent controls.

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

Double strike

When Raving Brigand enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice an Omen, target player mills three cards.

Razing Throng's power and toughness are each equal to the number of creatures you control.
Whenever one or more cards are put into exile from anywhere, create a 1/1 white Cleric creature token.
{2}{W}{W}: Exile a nonland card from a graveyard. You gain 3 life.

Whenever another creature you control dies, target player loses 1 life and you gain 1 life.
{1}{B}, Sacrifice a creature: Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

Create two 1/1 colorless Servo artifact creature tokens.
Leitmotif (If you cast this spell from your hand, exile it as it resolves. When you next cast a spell that shares a color with this card, you may cast this from exile without paying its mana cost.)

Flying, ward {2}
Whenever Realm Crossers deals combat damage to a player, create a blue enchantment token named Tambo with “At the beginning of your upkeep, draw a card if you control a Scout.”

Reach
Whenever you cast a spell with mana value 5 or greater, Reaper Squad deals 3 damage to target player or planeswalker.

Return target instant or sorcery card from your graveyard to your hand.
Draw a card.

Tap up to three target lands. They don't untap during their controller's next untap step.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Starting with you, each player either passes or reveals the top card of their library. Each player that revealed a card this way pays life equal to its mana value. If a player can't, that player passes. Then each player who hasn't passed yet puts that card into their hand. Repeat this process until each player has passed.

{2}{B}: Reclaimed Kalak gains indestructible until end of turn.
Revive {3}{W} ({3}{W}, 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.)

Whenever a creature you control deals combat damage to an opponent or planeswalker, put a technology counter on Reclamation Project.
Remove X technology counters from Reclamation Project: You may cast target artifact or creature card with mana value X from your graveyard this turn. That creature enters as an artifact in addition to its other types. X can't be 0.

As an additional cost to cast this spell, pay {2} or sacrifice a creature.
Menace

When Recursion Runner enters, create a Function token with “If this spell isn't a copy, copy it. You may choose new targets for the copy.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

When Red-Crowned Admiral enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Each creature you control with a +1/+1 counter on it has flying.