msem-instigator

(Transforms from Ruined Theater.)
{T}: Add one mana of any color.

{T}: Add {C}.
{3}, Exile Resurgent Oasis from your graveyard: Choose a basic land type. Create a tapped colorless land token that's a Desert and the chosen basic land type.

Target opponent chooses a creature card in your graveyard. Return the chosen card from your graveyard to your hand.

[+2]: Each player sacrifices a creature. Then each player who did creates a 1/1 white and black Spirit enchantment creature token.
[–X]: You may put an enchantment card with mana value X or less from your hand onto the battlefield.
[–6]: Shuffle, then reveal the top seven cards of your library. Put any number of enchantment cards from among them onto the battlefield. Shuffle the rest into your library.

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.

Enchant creature
As long as enchanted creature has toughness 3 or less, it can't attack or block.

Codex — Ser Wayver, the Broken Hour; Suzume Oshiruko; Aguri, Shadow of Doubt; Sukhar, Consort to the Dark; Chi Lee of the Underworld. (As this enters, conjure its contents into a shuffled face-up additional library.)
You may spend mana as though it were mana of any color to cast this codex's contents.

Whenever you cast an instant or sorcery spell, put a loyalty counter on Reytali of Endless Muses.
[0]: Add X mana in any combination of colors, where X is the number of spells you've cast this turn.
[–3]: Create two 3/1 red Sand creature tokens with haste.

{1}{G}: Rhudai Pathfinder gets +X/+X until end of turn, where X is the number of differently named lands you control. Activate only once each turn.

Rice Fields enters tapped.
{T}: Add {W} or {U}.
When Rice Fields enters, you may put a loyalty counter on a planeswalker you control.

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

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{1}: If you control ten or more nonland permanents, unlock Riddle of Entropy.
As long as the revealed card is a permanent card, each nonland permanent you own is a copy of it.

Target creature gets -2/-2 until end of turn.
{3}{B}, Exile Rift Splicing from your graveyard: Aetherize target creature card with mana value 3 or less in a graveyard. Activate only as a sorcery. (To aetherize, create a token that's a copy of it, then exile that token.)

{T}: Add {C}.
{3}, {T}: Add {C} for each basic land you control.

Riga's Workshop enters tapped.
When Riga's Workshop enters, you may mill two cards.
{T}: Add {U} or {R}.

Put a +1/+1 counter on up to one target creature.
Draw a card.

Scry 1, then you draw a card and you lose 1 life.

Riko's Academy enters tapped.
When Riko's Academy enters, you may mill two cards.
{T}: Add {R} or {W}.

{T}: Exile target creature you control.
{2}, {T}: Target creature you control becomes a copy of a card exiled with Ring of Remembrance until end of turn.
{4}, {T}, Sacrifice Ring of Remembrance: Each creature becomes a copy of a card exiled with Ring of Remembrance until end of turn.

As long as equipped creature has power 3 or less, it can't be blocked and it can't be the target of spells and abilities you don't control.
Equip {1}
Whenever Ring of Souls becomes attached to a creature, an opponent of your choice may create a 2/2 black Spirit creature token.

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.

Ripplecore Trails enters tapped.
{T}: Add {R} or {G}.
{R}{G}, {T}, Sacrifice Ripplecore Trails: Conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

Rippling Core enters tapped.
{T}: Add {R} or {W}.
{R}{W}, {T}, Sacrifice Rippling Core: Conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
When Risen Looter enters, if it engorged a noncreature, nonland card, draw a card, then discard a card.

Vanishing 3 (This permanent enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When the last time counter is removed from Rising Riots, destroy target land.