msem-instigator

Disgraced 2 (This enters with two -1/-1 counters. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
When Branded Contractor dies, you may put its counters on target creature.

First strike
Other Rogues you control get +1/+0 and have first strike.
{2}, Sacrifice a permanent: Return target Rogue card from your graveyard to your hand.

When Breaker of Secrets enters the battlefield, each player mills three cards from each of their libraries.
Recite {U} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters the battlefield or if it would leave the battlefield.)

Breezerider has flying as long as you control a Nymph.
Breezerider has hexproof as long as you control another Monkey.

Flying, trample
Whenever Bretala of Redsky attacks, it gains double strike until end of turn unless defending player sacrifices a creature.

Prowess
Unveil {2}{U}{R} ({2}{U}{R}: Transform this. Unveil only as a sorcery.)

Flying, haste
At the beginning of the end step, sacrifice Brightflame Phoenix.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Flash
When Brightsouled Guardian enters the battlefield, return up to one target nonland permanent to its owner's hand.

Prowess, trample
Whenever Brilliant Diviner deals combat damage to a player, draw a card.

{2}{R}: Target creature can't block Brimstone Courser this turn.
Ride {3}{R}{R} ({3}{R}{R}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Whenever Brine Kelpie attacks, you may tap target creature an opponent controls.
Ride {2}{U} ({2}{U}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Whenever you draw a card, you may have target player mill two cards.

Bristling Skoki has first strike as long as it's attacking.
Whenever Bristling Skoki blocks a creature, you may have it deal damage equal to its toughness to that creature.

Flash
Whenever you cast your second spell each turn, put a +1/+1 counter on Brooding Replacement.

Reach
Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Glorious end — When Brutal Champion dies, if it was tapped, each opponent sacrifices a creature.

Whenever another creature enters the battlefield, Brutish Champion fights that creature.

Whenever you cast a spell for its showcase cost, create a 2/2 blue Drake creature token with flying.

{3}{U}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

When Bug Catcher enters the battlefield, create a 1/1 green Insect creature token.
Whenever a nontoken Insect you control dies, create a 1/1 green Insect creature token.

First strike
Ascend {1}{B} ({1}{B}: Exile this creature, then return it to the battlefield transformed. Ascend only as a sorcery.)

Whenever Burning Hart deals combat damage to a player, it deals that much damage to up to one target planeswalker that player controls.

Haste
Sacrifice another creature: Bygone Aristocrat gains indestructible until end of turn.

When Byron, Unlikely Hero enters the battlefield, put a +1/+1 counter on each other Citizen or Peasant you control.
Whenever a nontoken creature you control with a +1/+1 counter on it dies, create a 1/1 white Peasant creature token.

Haste
Revive {3}{R} ({3}{R}, Exile this card from your graveyard: Create a token that's a copy of this card, except it has no mana cost. Activate this ability only any time you could cast a sorcery.)