msem-instigator

{U}, {T}: You may tap or untap another target creature.
Whenever one or more other creatures you control deal combat damage to a player, you may untap Riverchase Diver.

Harmony — Untap target permanent.
Whenever you cast an instant or sorcery spell, harmonize. (Trigger up to one harmony of one permanent you control.)

Flying
Whenever Rivha and at least two other creatures attack, exile all other attacking creatures you control. For each creature exiled this way, create a 3/3 white Angel creature token with flying that's tapped and attacking.

First strike
Whenever a creature dealt damage by Roadside Reaper this turn dies, you may discard a card. If you do, put a +1/+1 counter on Roadside Reaper and draw a card.

Trample
Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)

At the beginning of combat on each of your turns, you may sacrifice a land or exile a land card from your graveyard. If you do, create two 1/1 red Goblin creature tokens with haste. Exile those tokens at the beginning of the next end step.

Deploy 2 (As this enters, you may tap any number of other creatures you control with total power 2 or more.)
When Rogue Groundskeeper enters deployed, exile up to two target cards from a single graveyard.

Whenever you cast a modal instant or sorcery spell, draw a card.
{W}{U}{B}{R}{G}: Copy target modal instant or sorcery spell. You may reselect modes and choose new targets for the copy, and you may choose an additional two modes and may choose the same modes more than once.

Flying
When Rooftop Robber enters, another target Pirate or Rogue you control gets +2/+0 and can't be blocked this turn.

When Rootbound Awakener enters, create a green Aura enchantment token named Vivification attached to target creature or land. The token has enchant creature or land and “Enchanted permanent is a creature with base power and toughness 5/5 in addition to its other types.”

Instant, sorcery, and enchantment spells you cast cost {1} less to cast.

When Rotting Sunseeker dies, return target creature card with power 2 or less from your graveyard to your hand.

Vigilance
When Roya Ritualist enters or whenever you cast a spell, if {G}{U} was spent to cast it, draw a card, then you may put a land card from your hand onto the battlefield tapped. Put a +1/+1 counter on Roya Ritualist.

Ward {2}
Foresight — Whenever you draw your second card each turn, Royal Falconer gains flying until end of turn.

Royster Hounds can't be blocked by creatures with power 2 or less.

As long as you control another artifact, Ruin Guardian gets +1/+1.

Haste
Ruin Shark attacks each turn if able.
Ruin Shark gets +1/+0 and has first strike as long as you've drawn two or more cards this turn.

Whenever you cast a cryptic spell, creatures you control get +1/+1 until end of turn. (Artifacts, enchantments, and modal spells are cryptic.)

At the beginning of combat on your turn, Ruination's Hand gains flying until end of turn if a creature you control or a creature card in your graveyard has flying. The same is true for first strike, double strike, deathtouch, hexproof, haste, indestructible, lifelink, menace, reach, trample, and vigilance.

Trample
Whenever a noncreature permanent is put into a graveyard from the battlefield, put a +1/+1 counter on Ruinous Naga.

{1}, Sacrifice Ruinous Proselyte: Destroy target artifact or nonbasic land.

Defender, flying
Ruins Guardian can attack as though it didn't have defender as long as a creature died under your control this turn.
Whenever Ruins Guardian attacks, you may exile two creature cards from your graveyard. If you do, draw a card.

Ruins Pack gets +2/+2 as long as you sacrificed a permanent this turn.

When Runebreaker Mage enters, return another target nonland permanent you control and target nonland permanent you don't control to their owner's hands.