msem-instigator

[+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.

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.

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.

{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}.

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

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.”)

{T}: Add {C}.
{T}, Reappropriate: Add {W} or {U}. (Exile exactly two cards from your hand and/or graveyard.)

{T}: Add {C}.
{1}: Risti Workshop becomes a creature in addition to its other types until end of turn.
When Risti Workshop deals combat damage to an opponent, you may sacrifice it. If you do, search your library for a basic land card, put it onto the battlefield, then shuffle.

({T}: Add {U} or {R}.)
As Ritzy Parlor enters, you may pay {1}. If you don't, Ritzy Parlor enters tapped.

{T}, Pay 1 life: Add {W}.
{6}{W}{W}{W}, Exile Rius, Temple of the Grandfather from your hand: Target player gains 20 life.

Riv's Safehouse enters tapped.
When Riv's Safehouse enters, you may mill two cards.
{T}: Add {U} or {B}.

As long as your deck contains only blue and colorless cards, your minimum deck size is reduced by eight.

({T}: Add {U} or {R}.)
Roaring Cascade enters tapped.

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Rosegill Rover can't be blocked.
Whenever Rosegill Rover attacks, you may discard a card. If you do, draw a card.

This land enters tapped. As it enters, choose a color.
{T}: Add one mana of the chosen color.
{1}, {T}, Sacrifice this land: Target creature seeks secrets. (Give it that Oath Aura. Fulfill it by attacking with it and two or more other creatures to draw a card.)

Rot-Sand Ruins enters tapped unless you control another Desert.
{T}: Add {B} or {G}.

Rousing Path enters tapped unless you control one or fewer other lands.
{T}: Add {U} or {R}.
Cycling {2} ({2}, Discard this card: Draw a card.)

({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.