msem-instigator

Choose one —
• Change all targets of target spell or ability.
• All damage that would be dealt to target creature this turn is dealt to another target creature instead.

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.

Create a token that's a copy of target creature, except it has haste and “At the beginning of the end step, sacrifice this permanent.”
Flashback {1}{G}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Shimmer (Whenever this creature attacks, create a tapped and attacking token that's a copy of it. Exile the token at the beginning of the next end step.)

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

Wu Xing (Add effects based on the number of colors of mana spent to cast this spell.)
1 | Refulgent Flare deals 3 damage to any target. If a permanent dealt damage this way would die this turn, exile it instead.
3 | You gain 3 life.

Destroy all monocolored creatures.

Return target creature you own to your hand.
Scry 1.

When Refuse Trawler enters, you may pay {G}. If you do, choose one —
• Return a permanent card from your graveyard to your hand.
• Rediscover a permanent card. (Look at the top card of your library. You may reveal it and put it into your hand if it's a permanent card. Otherwise, put it back or into your graveyard.)

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

Counter target spell.
{1}{U}, Exile Refute from your graveyard: Draw a card.

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.)

Menace
Regal Dragoon gets +1/+1 as long as you control a legendary creature.

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

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
As long as you control three or more artifacts, Regal Seasnake has vigilance. (Attacking doesn't cause it to tap.)

Whenever Regretful Chronicler is dealt damage, put a +1/+1 counter on it. (It must survive the damage to get the counter.)
Surpass {5}{U} ({5}{U}: Transform this. This
costs 1 less to activate for each counter on it. Activate only as a sorcery.)

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.

Amass Soldiers 2. (Put two +1/+1 counters on an Army you control. It's also a Soldier. If you don't control one, create an 0/0 black Soldier Army creature token first.)
Flashback {3}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Return target permanent card from your graveyard to your hand. If it's an enchantment card, create a 2/2 black Zombie creature token.

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.

Menace

At the beginning of combat on your turn, you may have Regurgitator Ooze consume. If you do, it gets +2/+2 until end of turn. (To consume, sacrifice another creature or exile a creature card from your graveyard.)
When Regurgitator Ooze dies, return a card exiled with it to its owner's hand.

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.

Choose two —
• You gain 3 life.
• Tap target creature.
• Put a +1/+1 counter on target creature.

Trample
{1}{B}: Rehis-Dorahn Plowbeast gets +1/+1 until end of turn.