msem-instigator

Target creature you control gets +2/+2 until end of turn and must be blocked this turn if able.

All creatures able to block Raiun Bay Merchant do so.

Art of war — At the beginning of your end step, if Raiun Bay Scourge dealt damage to an opponent this turn, gain control of target artifact or enchantment until Raiun Bay Scourge leaves the battlefield.

When Rakkiri Aspirant enters, if you control an embattled creature, exile the top card of your library. Until end of turn, you may play that card. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Rakkiri Initiate gets +0/+2 as long as it's embattled. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Rakkiri Piker has double strike as long as it's embattled. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Create three 1/1 white Soldier creature tokens. If you control an attacking creature, they're tapped and attacking. If you control a blocking creature, they're blocking target attacking creature.
Quickdraw {2}{W} (When a creature you control blocks or becomes blocked, you may cast this for {2}{W}.)

Deception {2}{U}{U} ({2}{U}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Raloran Insurgent deals combat damage to a player, abound. (You may cast a spell that costs less than this from your hand without paying its mana cost.)

Whenever Ram Wrangler attacks, until end of turn, gain control of target creature defending player controls with power less than or equal to the number of creatures in Ram Wrangler's pack. Tap it. It's attacking defending player. (Two or more creatures you control with equal power are in a pack.)

At the beginning of your end step, if a permanent you controlled left the battlefield this turn, put a party counter on Rambunctious Afterparty. Then Rambunctious Afterparty deals damage equal to the number of party counters on it to each opponent.

Rammanethi Hydroshaper gets +1/+1 as long as you control an Island.
{2}{U}: Target creature blocking or blocked by Rammanethi Hydroshaper gets -1/-0 until end of turn.

Reach (This creature can block creatures with flying.)
Whenever a land you control enters, Rammanethi Sandshaper deals 1 damage to target creature with flying.

When Rampaging Xiangshe enters, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Each creature you control with a +1/+1 counter on it has trample.

At the beginning of your upkeep, mill two cards.

Defender, reach
Bulwark — {X}, {T}: Rampart Ballista deals X damage to each opponent. X can't be greater than the number of creatures you control with toughness 4 or greater.

Equipped creature gets +2/+3 and has reach.
Equip Scout or Archer {1}
Equip {3}

Flying
When Rapacious Regent enters, you may sacrifice another creature or artifact. If you do, Rapacious Regent deals 3 damage to any target.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)

When Rat King enters, create two 1/1 black Rat creature tokens with “This creature can't block.”
Whenever Rat King or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Choose one or both —
• Each player sacrifices an artifact.
• Each player sacrifices an enchantment.

Whenever Ravencaller or another creature enters from your graveyard, create a 1/1 blue Bird creature token with flying.

Whenever one or more other creatures you control deal combat damage to an opponent, choose one —
• That player discards a card at random.
• That player sacrifices a creature with toughness 4 or less.

The second spell you cast each turn costs {2} less to cast.
Whenever you cast a spell, each opponent loses 1 life and you gain 1 life.

Ravenous Grue enters with a menace counter on it.
{5}{B}{B}, Remove a menace counter from Ravenous Grue: Destroy target creature.

Lifelink
When Ravenous Tarwurm enters, you may have it consume. When you do, it deals 3 damage to target creature. (To consume, sacrifice another creature or exile a creature card from your graveyard.)