msem-instigator

At the beginning of your upkeep, if a library has twenty or fewer cards left in it, return Returned Explorer from your graveyard to the battlefield tapped.

As an additional cost to cast Reunite with Nature, sacrifice X creatures.
Create X plus one 3/1 red and green Elemental Horror creature tokens with haste and trample.

Archive 3 (As this enters, shuffle the top three cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, put the top card of your main library on the bottom of the archived library.
{U}: Exchange a card from the archived library with a card from your hand.

Foretell {3}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
This spell's foretell cost costs {3} less to pay if an opponent drew two or more cards this turn.
Create a 5/5 green Beast creature token with trample.

When Reverence Seeker dies, you may return another target Knight card from your graveyard to your hand.

Reverent Flame deals 3 damage to target creature. Create three Idol tokens. (They're artifacts with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

This spell can't be countered.
Exile your library, then shuffle Revisionary Studies, your graveyard, and your hand into your library. Draw five cards.

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.

Return target permanent card from your graveyard to your hand. You gain 3 life.

{2}, Sacrifice a creature or Rewards of Ruthlessness: Creatures you control get +1/+0 until end of turn.

When Rework the Canvas enters, purge. (Exile two cards that share a type from graveyards. If you do, draw a card.)
Whenever one or more cards are put into exile from anywhere, you gain 2 life and scry 1.

Ward {2}
When Rewriter of Flesh enters, target creature you control becomes an enchantment and loses all other card types. (It still has its abilities, but it's no longer a creature.)

When Rhudai Overseer enters, look at the top four cards of your library. You may reveal an artifact or enchantment card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Whenever Rhudai Swathcutter attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

(Activate each submodule once as a sorcery. When this enters, activate one submodule for free.)
{4}{R}: Hymn
Exile the top three cards of your library. During your next turn, you may play those cards.
{4}{W}: Chorus
Create three 1/1 white Avatar enchantment creature tokens with prowess.
{3}{R}{W}: Beat
Rhythm Module gains “Whenever you cast a noncreature spell, creatures you control get +1/+0 and gain haste until end of turn.”

{T}, Sacrifice Rickety Guildhall: Search your library for a Forest or Island card and put it onto the battlefield tapped, then shuffle.

Equipped creature gets +2/+2 and has reach and protection from enchantment creatures. (It can't be blocked, targeted, or dealt damage by enchantment creatures.)
Equip {3}

Target creature you control and each other creature with the same name as that creature get +3/+3 and gain trample until end of turn.

Target creature you control gets +2/+2 and gains lifelink until end of turn. It fights up to one target creature you don't control.

Flying
Whenever Rimebreath Tyrant attacks, you may discard a card. When you do, tap target creature. It doesn't untap during its controller's next untap step.

Flying
When Rimecraft Owl enters, you may put an Aura card with mana value 3 or less from your hand or graveyard onto the battlefield attached to Rimecraft Owl or target creature an opponent controls that Aura could enchant.

{T}: Add one mana of any color. Activate only if you control a multicolored permanent or there is a multicolored card in your graveyard.

First strike
Engage (This creature must be blocked each combat if able.)

Foretell {2}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Attacking creatures get +2/+0 until end of turn. If this spell was foretold, those creatures also gain trample until end of turn.

Ripping Wilds enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Ripping Wilds: You may put up to two basic land cards from your hand onto the battlefield tapped.