msem-instigator

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.

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}

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

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

Riko's Academy enters the battlefield tapped.
When Riko's Academy enters the battlefield, 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.

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

Ripping Wilds enters the battlefield 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 the battlefield 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 the battlefield 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.”)

At the beginning of your end step, aetherize target permanent you control. (To aetherize, create a token that's a copy of it, then exile that token.)

{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 the battlefield, you may pay {1}. If you don't, Ritzy Parlor enters the battlefield 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 the battlefield tapped.
When Riv's Safehouse enters the battlefield, 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 the battlefield tapped.

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

Whenever Rolling Homestead becomes a creature, nourish 1. (To nourish 1, either put a +1/+1 counter on this creature or create a 1/1 white Citizen creature token.)
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

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

Rosesworn Knight gets +1/+1 as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

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

({T}: Add {R}.)
Rousing Rubble enters the battlefield tapped.
Double strike
{2}{R}{R}: Rousing Rubble becomes a creature in addition to its other types until end of turn.