msem-instigator

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.

Each instant and sorcery card in your hand has orchestrate. Its orchestrate cost is equal to its mana cost reduced by {2}. (You may exile those cards from your hand anytime you could cast a sorcery for their orchestrate cost. When you next resolve a spell, you may cast it from exile without paying its mana cost.)
When you cast your third spell this turn, exile Reytali, then return her to the battlefield transformed.

Discard any number of cards, then sacrifice any number of artifacts. Draw X cards, where X is one plus the number of cards discarded and artifacts sacrificed this way.

Rhudai Fieldtiller gets +1/+1 for each enchanted land you control.
At the beginning of your end step, untap each enchanted land you control.

{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.

Whenever Rhudai Swathcutter attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Prowess

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}

Target creature you control and each other creature with the same name as that creature get +3/+3 and gain trample until end of turn.

Primal {R} (During your turn, you may cast this spell for {R} instead of playing a land.)
Target creature gets +4/+0 and gains trample until end of turn.

Trample
Rift Prowler enters with X +1/+1 counters on it, where X is your fealty to Forests. (Each Forest you control counts towards your fealty to Forests.)

Wanderlust — When Riftbreaker Mage dies, if you control four or more differently named lands, Riftbreaker Mage deals damage equal to its power to each opponent.

Flying, menace
When Riftkeeper Entity enters, discard your hand, then draw cards equal to the number of differently named lands you control.
{1}{R}, Discard Riftkeeper Entity: Create a tapped colorless land token named Fading Rift with “{T}, Sacrifice this land: Add one mana of any color.”

{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.”

If you control a Mountain, you may sacrifice an Aura rather than pay this spell's mana cost.
Righteous Bolt deals 2 damage to any target.

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

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.

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