msem-instigator

When Repurposed Custodian enters, shuffle any number of target cards from graveyards into their owner's libraries.

{2}, Sacrifice Research Aquarium: Draw a card.
When Research Aquarium is put into a graveyard from the battlefield, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

({T}: Add {G} or {W}.)
Whenever Resplendent Substratum becomes tapped, you lose 1 life unless you control two or more basic lands.

When Restless Explorer enters, search your library for a land card, reveal it, put it into your hand, then shuffle.

Restored Automaton enters with X +1/+1 counters on it.
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

(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.

Look at the top two cards of your library. Put one into your graveyard and the other back on top.

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.

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.

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 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}.

{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 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.”)

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.)