msem-instigator

Menace
Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, each opponent discards a card.

Flying

When River Miscreants enters, target creature you control can't be blocked this turn.
{2}{U}: Return River Miscreants to its owner's hand. Activate only as a sorcery.

{1}, {T}: You gain 1 life.
{2}, {T}: Tap target creature.

{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.)

{7}{U}: Tap up to three target nonland permanents. This ability costs {2} less to activate if you control a legendary creature.

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.

When Rixia, Rift Shunted enters, target creature can't be blocked this turn.
Whenever a creature you control deals combat damage to an opponent, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)

As Road to Alratha enters, choose near or far.
Whenever you attack,
• Near — Creatures you control get +1/+1 until end of turn.
• Far — Put a +1/+1 counter on target creature you control. Untap it.

{2}, {T}: Tap target creature.

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.

You may play this card transformed.
Trample

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

Flying
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Flash
Enchant creature
When Roar of the Wilds enters, enchanted creature gets +3/+3 until end of turn.
When enchanted creature dies, create a 1/1 green Saproling creature token.

({T}: Add {U} or {R}.)
Roaring Cascade enters tapped.

{1}{R}: Roaring Dracowyrm gets +2/+0 until end of turn. Activate only once each turn.

Whenever Roaring Illusion attacks alone, for each other creature you control, create a token that's a copy of that creature and that's tapped and attacking. Exile those tokens at the beginning of the next end step.

Enchant creature
Enchanted creature gets +2/+1 and is a black Zombie in addition to its other colors and types.

Discard Robocamel: Create a Food token. Activate only as a sorcery. (It's an artifact with “{2}, {T}, Sacrifice this artifact: You gain 3 life.”)

Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
Whenever Robot Herder deals combat damage to a player, create a 1/1 colorless Servo artifact creature token.

When Rocket Admin enters, you may pay 3 life. When you do, gain control of target creature or planeswalker with mana value 3 or less until its owner pays {3}.

If a creature an opponent controls would die, exile it instead.
Whenever Rocket Poacher deals combat damage to a player, put a card exiled with it onto the battlefield under your control.

Trample
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Rockpounding Saurian enters, if tribute wasn't paid, you may destroy up to one target artifact, up to one target land and up to one target Fortress.