msem-instigator

At the beginning of your upkeep, if an opponent has more life than you, create a 4/4 red Elemental creature token with haste and “Creatures blocking this creature have winnow.” (Damage dealt to a creature with winnow causes its controller to lose that much life.)

River's Wrath deals 2 damage to any target. If you've been dealt damage this turn, River's Wrath deals 4 damage instead.

First strike
Whenever a creature dealt damage by Roadside Reaper this turn dies, you may discard a card. If you do, put a +1/+1 counter on Roadside Reaper and draw a card.

Creatures you control get +2/+0 and gain menace until end of turn. (They can't be blocked except by two or more creatures.)

{1}{R}: Roaring Dracowyrm gets +2/+0 until end of turn. Activate only once each turn.

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.

Trample
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Rockpounding Saurian enters, if tribute wasn't paid, you may destroy up to one target artifact, up to one target land and up to one target Fortress.

At the beginning of combat on each of your turns, you may sacrifice a land or exile a land card from your graveyard. If you do, create two 1/1 red Goblin creature tokens with haste. Exile those tokens at the beginning of the next end step.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its costs.)
{1}{R}, Discard a red card: Roggar deals 2 damage to any target. This damage can't be prevented.
{2}{R}, Exile a red card from your graveyard: Create two tapped 1/1 red Elemental creature tokens.

Roggar's Frenzy deals 3 damage to any target.
{2}{R}, Exile Roggar's Frenzy from your graveyard: Create two tapped 1/1 red Elemental creature tokens.

Roggar's Gambit deals 2 damage to any target.
Reprise {1}{R} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)
Damage dealt by sources reprising Roggar's Gambit can't be prevented.

Choose one —
• Destroy target artifact.
• Target creature gets +2/+1 and gains first strike until end of turn.
Kindle 2—{3}{R} ({3}{R}, Exile this card from your graveyard: Create two 1/1 colorless Elemental creature tokens. Kindle only as a sorcery.)

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever a creature you control attacks alone, add a quest counter.
Target creature can't block this turn.
Gain control of target creature until end of turn. Tap it. It becomes attacking.
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Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

When Roseblood Hart enters, choose one —
• Destroy target artifact.
• Create a Treasure token.

Instant, sorcery, and enchantment spells you cast cost {1} less to cast.

Prowess
When Rosebud Runner enters, exile the top card of your library. During your next turn, you may play that card from exile.

({T}: Add {R}.)
Rousing Rubble enters tapped.
Double strike
{2}{R}{R}: Rousing Rubble becomes a creature in addition to its other types until end of turn.

Whenever Roving Dreadnought attacks, you may salvage a card that was put into your graveyard this turn. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

Gain control of up to two target creatures until end of turn. Untap them. They gain haste until end of turn.
Menagerie — If there are five or more creature types among creatures you control, untap all creatures you control. Until end of turn, they gain “{T}: This creature fights another target creature.”

When Royal Retriever enters or when a creature scavenges it, you may discard a card. If you do, draw a card.
Scavenge {R} ({R}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

Flying
Whenever Rubble Scavenger deals combat damage to a player, you may return target artifact card with mana value 4 or less from your graveyard to the battlefield.

When Rubble Seer enters, you may sacrifice a land or exile a land card from your graveyard. If you do, exile the top card of your library. Until the end of your next turn, you may play that card.

Choose target creature, then choose two —
• The chosen creature gets +3/+0 until end of turn.
• The chosen creature gains trample until end of turn.
• The chosen creature gains first strike until end of turn.

Haste
Ruin Shark attacks each turn if able.
Ruin Shark gets +1/+0 and has first strike as long as you've drawn two or more cards this turn.