msem-instigator

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.)

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.)

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

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

Creature tokens you control get +1/+1 and can block an additional creature each combat.

Flying

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

{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.)

Flash
{U}, Return another creature you control to its owner's hand: Reclusive Archmage can't be blocked this turn and gains hexproof until end of turn. Activate only once each turn.

Trample, haste
When Red Pelt Hart deals combat damage to a player, return it to its owner's hand.
At the beginning of your end step, sacrifice Red Pelt Hart.

Indestructible
When Reflected Worldwalker enters, each player puts their hand into their sideboard.

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.)

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.

Whenever a creature dealt damage by Rei's Betrayer this turn dies, you gain life equal to that creature's toughness.

Remarkable Hunter must be blocked if able.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
When Returned Bokor dies, return it to its owner's hand.

Flying
Whenever Revived Pterosaur deals combat damage to an opponent, that player discards a card.
{4}{B}{B}, Discard two cards: Return Revived Pterosaur from your graveyard to the battlefield tapped.

Flying
Rezzal, the Loamfeaster gets +1/+1 for each nonland card exiled with it.
You may play lands exiled with Rezzal.
{1}{B/G}: Exile target card from an opponent's graveyard. Activate only outside of combat.

First strike, lifelink
Tribute 4 (As this creature enters, an opponent of your choice may put four +1/+1 counters on it.)
When Righteous Priestess enters, if tribute wasn't paid, the chosen player can't cast creature spells during their next two turns.

Concord — When Riptide Mystic enters, if there are four or more card types among permanents you control, you may return target nonland permanent to its owner's hand.

Whenever Roaring Illusion attacks alone, for each other creature you control, create a token that's a copy of that creature and that's tapped and attacking. Exile those tokens at the beginning of the next end step.

Discard Robocamel: Create a Food token. Activate only as a sorcery. (It's an artifact with “{2}, {T}, Sacrifice this artifact: You gain 3 life.”)

If a creature an opponent controls would die, exile it instead.
Whenever Rocket Poacher deals combat damage to a player, put a card exiled with it onto the battlefield under your control.