msem-instigator

Whenever Bound Apparition becomes the target of a spell or ability, put a -1/-1 counter on it.

Flying, prowess
When Bound Watcher enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

When Boundary Hallowblade enters, create a white Aura enchantment token named Consecration Blessing attached to target land. The token has enchant land and “Enchanted land is named Hallowed Ground and has indestructible.”

Harmony — Create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”
When Bouquet Singer enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Whenever Bourasan Street Watch attacks, you may pay {W}. If you do, Bourasan Street Watch gains indestructible until end of turn.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
When you unveil Bramble Quickling, you may have it fight target creature.

Branch Prowler can't be blocked except by creatures with flying.

Haste
You may exert Brash Charger as it attacks. When you do, creatures with power 1 or less can't block this turn. (An exerted creature won't untap during your next untap step.)

Sacrifice another creature: Brash Hunter deals 1 damage to any target.
At the beginning of your end step, if three or more creatures died this turn, transform Brash Hunter.

Double strike
{1}{R}{W}: Target creature gains double strike until end of turn. Activate only if Bravery is in your graveyard.

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.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Brazen Chimera can't be blocked except by three or more creatures as long as it has a +1/+1 counter on it.

Trample
Whenever Breaker of Cities deals combat damage to a player, create a 1/1 white Soldier creature token with vigilance.
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

When Breaker of Secrets enters, 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 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.

If you would draw a card, you may instead choose creature or land and exile cards from the top of your library until you exile a card of the chosen kind. Put that card into your hand and put all other cards exiled this way on the bottom of your library in a random order.

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, 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.

Flying
When Brilliant Griffin enters, target creature gets +2/+2 until end of turn.

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

At the beginning of your upkeep, you may discard a land card. When you do, create a 2/2 green Wolf creature token.

Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)
When Bristling Baron dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control.

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.

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