msem-instigator

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 Flower Assassin enters, destroy target creature.
Revive {5}{B} ({5}{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.)

First strike
Redeye Commando's power is equal to twice the number of artifacts you control.
Redeye Commando attacks each turn if able.
Whenever Redeye Commando attacks, if its power is 6 or greater, it gains menace and trample until end of turn.

Counter target spell unless its controller pays its mana cost. (For example, if a spell costs {1}{U}{U}, its controller must pay {1}{U}{U}.)

First strike
Whenever an opponent casts a noncreature spell, you gain 2 life.

Target player sacrifices a creature. Then you gain 3 life if that player doesn't control any creatures.

Whenever you draw a card, put a hatch counter on Reefcrown Egg.
{T}, Sacrifice Reefcrown Egg: You may put a creature card with mana value less than or equal to the number of hatch counters on Reefcrown Egg from your hand onto the battlefield.
Cycling {2} ({2}, Discard this card: Draw a card.)

At the beginning of your upkeep, return target enchantment card from your graveyard to your hand.
Whenever Reflect on Serenity or another enchantment you control enters or leaves the battlefield, each opponent loses 1 life and you gain 1 life.

Each creature you control gets +1/+1 for each other creature you control with the same name.

Take an extra turn after this one. If this spell was cast from exile, take two extra turns after this one instead. Shuffle Reflected Moment into its owner's main library.
Prophecy {6}{U}{U} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

Each player exiles all permanents they control, draws that many cards, then puts up to that many permanent cards from their hand onto the battlefield. Exile Reform Reality.

Choose target player. Until end of turn, if a spell or ability that player controls would cause them to draw a card, each of their opponents draws a card instead.

Destroy all creatures. If a Reflection would be destroyed this way, its owner shuffles it into their library instead.

Destroy all monocolored creatures.

Refuse to Submit deals 3 damage to any target. If that target is an attacking creature, it deals 5 damage instead.

First strike, trample
Whenever Regal Coralhorn deals combat damage to a player or planeswalker, return target card with a cycling ability from your graveyard to your hand.
Cycling {2} ({2}, Discard this card: Draw a card.)

Each player sacrifices three lands. Regal Ignition deals 3 damage to each nonlegendary creature.

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, Regrets of Mortals gets +2/+0 until end of turn. You may discard a card. If you do, draw a card.

Legacy (You may play this side of this card only from your graveyard. Exile it if it would leave the battlefield or not resolve.)
At the beginning of your upkeep, you may return a creature card from your graveyard to your hand. If you do, you gain 2 life.

When Reha, Entropy's Call enters, you may search your library for any number of land cards with different names and exile them with harvest counters, then shuffle.
At the beginning of your upkeep, you may put a card that you own in exile with a harvest counter on it at random onto the battlefield tapped.

If one or more -1/-1 counters would be put on a creature an opponent controls, put twice that many -1/-1 counters on it instead.

Rei, the Supplanter gets +1/+1 for each Forest you control.
At the beginning of each player's end step, if that player didn't play a land this turn, create a Forest token.

This spell costs {1} less to cast for each artifact you control.
Search your library for an artifact creature card with mana value X or less, put it onto the battlefield, then shuffle.

Harmony — Destroy target artifact or enchantment.
When Rejoicing Aristocrats enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Trample, haste
When Rejuvenating Elemental enters, remove up to X -1/-1 counters from among creatures you control. Rejuvenating Elemental gets +1/+1 until end of turn for each counter removed this way.