msem-instigator

Reveal the top X cards of your library, where X is the number of lands you control. Put any number of permanent cards revealed this way onto the battlefield and the rest on the bottom of your library in a random order.

You may have Reaping Willow assign its combat damage as though it weren't blocked.
{2}{G}: Reaping Willow gains indestructible until end of turn.

Return up to three target land cards from your graveyard to your hand.
Coalesce {6}{G} (You may cast this from your graveyard for {6}{G}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Put target artifact, enchantment, or card in a graveyard on the bottom of its owner's library.

Whenever Reclamation Grovesculptor enters or attacks, put a growth counter on target noncreature permanent. It becomes a colorless Forest land and loses all other card types and land types.

When Reclamation Sage enters, you may destroy target artifact or enchantment.

Flash

When Reconnaissance Expert enters, mill four cards.
When Reconnaissance Expert dies, return target noncreature permanent card from your graveyard to your hand.

Destroy target noncreature permanent. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Other creatures you control get +0/+1.
{T}: Add {G}.

Redleather Armorer gets +1/+1 as long as it's your turn.

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

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.)

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

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.

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

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Reveal the top two cards of your library. Put up to one land card from among them onto the battlefield and the rest into your graveyard.
III — Until end of turn, target creature gets +X/+0 and gains indestructible, where X is the number of lands you control.

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

When Rei's Cultivator enters, create a green Aura enchantment token named Sowing Spring attached to target land. The token has enchant land, “Enchanted land's name is Flowering Expanse” and “Whenever enchanted land is tapped for mana, add one mana of any color.”

Reach
{2}{G}: Rei's Ranger gets +2/+0 until end of turn.

Reach
{G}, Sacrifice Rei's Watch: Untap all creatures you control.

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.

When Reincarnation Savant dies, manifest the bottom card of your library. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Whenever a creature you control perseveres this turn, you gain 3 life. (A creature perseveres when it survives damage.)

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.