msem-instigator

At the beginning of combat on your turn, you may pay 3 life. If you do, target creature seeks secrets or valor. (Give it that Oath Aura. Fulfill secrets by attacking with it and two or more other creatures to draw a card. Fulfill valor by dealing combat damage to a player to create a 2/1 white Soldier token.)
Whenever you fulfill an Oath, each opponent sacrifices a nonland permanent.

(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.”

As Rhythm of Avaz enters, choose Cyrukan or Sahra.
• Cyrukan — At the beginning of combat on your turn, put a +1/+1 counter on target creature you control.
• Sahra — Creatures you control have menace and haste, and attack each combat if able.

As Rhythm of Danaj enters, choose Martoob or Tamaak.
• Martoob — At the beginning of your end step, return a nonland card at random from your graveyard to your hand.
• Tamaak — At the beginning of your end step, you may sacrifice a creature. If you do, draw cards equal to its power.

As Rhythm of Kaneh enters, choose Andazir or Mahara.
• Andazir — Whenever a creature you control attacks, defending player discards a card.
• Mahara — Whenever a nontoken creature you control dies, amass Soldiers X, where X is that creature's power.

As Rhythm of Nizev enters, choose Fahrib or Rahstahde.
• Fahrib — Whenever you cast a spell from anywhere other than your hand, draw a card.
• Rahstahde — Creatures you control have prowess. (Multiple instances of prowess stack.)

As Rhythm of Soli enters, choose Atieh or Kahroba.
• Atieh — Creatures you control have lifelink.
• Kahroba — Creatures you control enter with an additional +1/+1 counter on them.

Choose one —
• Destroy target monocolored creature.
• Ria-Demian Charm deals 2 damage to each creature.
• Each player discards two cards and loses 2 life.

First strike
Creatures you control attacking cause abilities of that creature to trigger as though it entered.

When Rice Cultivator enters, search your library for a basic Plains card or an artifact card with a mana ability, reveal it, put it into your hand, then shuffle.

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.

Whenever you cast a creature spell or create a creature token, you may exile target creature you control. Return it to the battlefield under its owner's control at the beginning of the next end step.

Whenever you cast a nonblue spell, create a 1/0 blue Horse Nymph creature token.
Horses get +1/+1 and have flying.

This spell costs {1} less to cast for each artifact and enchantment you control.
Reveal the top seven cards of your library. Put any number of noncreature, nonland cards from among them into your hand and the rest of the revealed cards into your graveyard.

Primal {R} (During your turn, you may cast this spell for {R} instead of playing a land.)
Target creature gets +4/+0 and gains trample until end of turn.

This spell costs {2} less to cast and may be cast as though it had flash if an opponent searched their library this turn.
When Ridge Warden enters, exile another target nonland permanent with mana value 4 or less until Ridge Warden leaves the battlefield.

Trample
Rift Prowler enters with X +1/+1 counters on it, where X is your fealty to Forests. (Each Forest you control counts towards your fealty to Forests.)

Flying, menace
When Riftkeeper Entity enters, discard your hand, then draw cards equal to the number of differently named lands you control.
{1}{R}, Discard Riftkeeper Entity: Create a tapped colorless land token named Fading Rift with “{T}, Sacrifice this land: Add one mana of any color.”

Whenever you cast a storied spell, you may pay {1}. If you do, draw a card. (Enchantments and legendary spells are storied.)
Sacrifice Right to Rule: Storied permanents you control gain indestructible until end of turn.

Other Humans you control get +1/+1.
Whenever Righteous Chaplain or another Human you control enters, tap target creature an opponent controls.

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.

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.

When Rigid Conformist enters, for each {W} spent to cast it, create a 1/1 white Human creature token.
Each creature you control gets +2/+2 if you control another creature with the same name as that creature.

Double strike
Whenever an opponent casts a noncreature spell, Riko, the Paragon deals 2 damage to that player.
Whenever a creature you control becomes blocked, untap it.

Whenever another creature you control enters, put a +1/+1 counter on it.
Whenever Rilken Preserver attacks, you may exile target nonland permanent you control, then return it to the battlefield under your control.