msem-instigator

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

Choose one or both —
• Riverboat Assault deals 3 damage to target creature.
• Target creature gets +3/+3 until end of turn.

{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.

Search your library for up to three basic land cards, reveal those cards, shuffle, then put one of them into the battlefield tapped, one into your hand and one on top of your library.

Return target creature or land card from your graveyard to your hand.

Look at the top five cards of your library. You may reveal a land or enchantment card from among them and put it into your hand. Then put the rest on the bottom of your library in any order.

{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.

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

Creatures you control get +2/+0 and gain menace until end of turn. (They can't be blocked except by two or more creatures.)

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.