msem-instigator

As Rhythm of Danaj enters, choose Martoob or Tamaak.
• Martoob — At the beginning of your end step, return a nonland card at random from your graveyard to your hand.
• Tamaak — At the beginning of your end step, you may sacrifice a creature. If you do, draw cards equal to its power.

As Rhythm of Kaneh enters, choose Andazir or Mahara.
• Andazir — Whenever a creature you control attacks, defending player discards a card.
• Mahara — Whenever a nontoken creature you control dies, amass Soldiers X, where X is that creature's power.

As Rhythm of Nizev enters, choose Fahrib or Rahstahde.
• Fahrib — Whenever you cast a spell from anywhere other than your hand, draw a card.
• Rahstahde — Creatures you control have prowess. (Multiple instances of prowess stack.)

As Rhythm of Soli enters, choose Atieh or Kahroba.
• Atieh — Creatures you control have lifelink.
• Kahroba — Creatures you control enter with an additional +1/+1 counter on them.

Counter target spell unless its controller pays {1}.
Metamorph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Choose one —
• Destroy target monocolored creature.
• Ria-Demian Charm deals 2 damage to each creature.
• Each player discards two cards and loses 2 life.

Prowess

First strike
Creatures you control attacking cause abilities of that creature to trigger as though it entered.

When Rice Cultivator enters, search your library for a basic Plains card or an artifact card with a mana ability, reveal it, put it into your hand, then shuffle.

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.

At the beginning of your upkeep, you lose 1 life and choose one —
• Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
• You may sacrifice an artifact. If you do, draw a card.

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.

Whenever you cast a creature spell or create a creature token, you may exile target creature you control. Return it to the battlefield under its owner's control at the beginning of the next end step.

Whenever you cast a nonblue spell, create a 1/0 blue Horse Nymph creature token.
Horses get +1/+1 and have flying.

This spell costs {1} less to cast for each artifact and enchantment you control.
Reveal the top seven cards of your library. Put any number of noncreature, nonland cards from among them into your hand and the rest of the revealed cards into your graveyard.

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.

This spell costs {2} less to cast and may be cast as though it had flash if an opponent searched their library this turn.
When Ridge Warden enters, exile another target nonland permanent with mana value 4 or less until Ridge Warden leaves the battlefield.

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.)

Target creature gets -2/-2 until end of turn.
{3}{B}, Exile Rift Splicing from your graveyard: Aetherize target creature card with mana value 3 or less in a graveyard. Activate only as a sorcery. (To aetherize, create a token that's a copy of it, then exile that token.)

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.