msem-instigator

{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}.

Enchant creature
Enchanted creature has “At the beginning of each player's end step, that player chooses another creature they control. That creature fights enchanted creature.”

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.

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.

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

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.

Rilken Forcefield Keeper gets +1/+1 for each enchantment you control.
Sacrifice Rilken Forcefield Keeper: Exile target permanent you control. Return that card to the battlefield under your control at the beginning of the next end step.

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.

Flying
Whenever Rimebreath Tyrant attacks, you may discard a card. When you do, tap target creature. It doesn't untap during its controller's next untap step.

Flying
When Rimecraft Owl enters, you may put an Aura card with mana value 3 or less from your hand or graveyard onto the battlefield attached to Rimecraft Owl or target creature an opponent controls that Aura could enchant.

{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.

Saga spells you cast cost {1} less to cast.

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

This spell costs {1} less to cast for each instant and/or sorcery card in your graveyard.
Once each turn, when you cast an instant or sorcery spell, you may create a 4/4 white Angel Cleric creature token with flying and vigilance.

First strike
Engage (This creature must be blocked each combat if able.)

Flying
{U}: Ripclaw Drake gets +1/-1 until end of turn.

This spell can't be countered.
Haste
Whenever a creature dealt damage by Ripper of the Fang Den this turn dies, put X +1/+1 counters on Ripper, where X is his power.

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.)

Flash
When Rippling Water Arcanist enters, copy target instant or sorcery spell you control, then return it to its owner's hand. You may choose new targets for the copy.