Breena, the Demagogue

Flying
Whenever a player attacks one of your opponents, if that opponent has more life than another of your opponents, that attacking player draws a card and you put two +1/+1 counters on a creature you control.

Olivia, Opulent Outlaw

Flying, lifelink
Whenever one or more outlaws you control deal combat damage to a player, create a Treasure token. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
{3}, Sacrifice two Treasures: Put two +1/+1 counters on each creature you control. Activate only as a sorcery.

Aya of Alexandria

Menace, lifelink
Whenever a historic creature you control deals combat damage to a player, create a 1/1 black Assassin creature token with menace. (Artifacts, legendaries, and Sagas are historic.)

Back in Town

Return X target outlaw creature cards from your graveyard to the battlefield. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)

Angelic Sell-Sword

Flying, vigilance
Whenever Angelic Sell-Sword or another nontoken creature you control enters, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."
Whenever Angelic Sell-Sword attacks, if its power is 6 or greater, draw a card.

Vihaan, Goldwaker

Other outlaws you control have vigilance and haste. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)
At the beginning of combat on your turn, you may have Treasures you control become 3/3 Construct Assassin artifact creatures in addition to their other types until end of turn.

Graywater's Fixer

Each outlaw creature card in your graveyard has encore {X}, where X is its mana value. (Exile it and pay its encore cost: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Ravine Raider

Menace (This creature can't be blocked except by two or more creatures.)
{1}{B}: Ravine Raider gets +1/+1 until end of turn.

Captain Lannery Storm

Haste
Whenever Captain Lannery Storm attacks, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Whenever you sacrifice a Treasure, Captain Lannery Storm gets +1/+0 until end of turn.