msem-instigator

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.”)

Bound by Nature enters with X nature counters on it.
You can't cast nonpermanent spells.
Creatures you control get +1/+1 for each nature counter on Bound by Nature and have “{T}: Add {G}.”

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.”

Flying
When Boundless Hopes enters, another target creature you control gains flying until end of turn.
Fleeting {U} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

{B}, {T}: Post a bounty on target permanent. (Put a bounty counter on that permanent. It has “When this permanent is put into a graveyard from the battlefield, each opponent draws a card” as long as it has a bounty counter on it.)
{B}, {T}, Pay 2 life: Destroy target creature with a bounty counter on it.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Bounty Crusher has trample as long as it's being blocked by a marked creature.

Whenever a creature with a counter on it dies, create a Gold token. (It's an artifact with “Sacrifice this artifact: Add one mana of any color.”)

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.)

Other Hounds you control get +1/+1.

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

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.

You may activate Boxue and Ma'Long's loyalty abilities an additional time if you've cast two or more spells this turn.
[+1]: Scry 2.
[–2]: Exile the top two cards of your library. You may play one of them this turn. When you do, put the other card into your hand.
[–6]: Whenever you cast a spell this turn, copy it. You may choose new targets for the copy.

[+1]: Boxue deals 1 damage to each opponent. You may draw a card, then discard a card.
[–1]: Create a Treasure token.
[–5]: Copy the next spell you cast this turn. You may choose new targets for the copy. (A copied permanent spell becomes a token.)

Trample
{1}{G}: Brackish Kelpie gets +2/+2 until end of turn. Activate only once each turn.

{1}, Sacrifice Brackwater Scuttler: Draw a card.

When Braenid Nomad enters, draw two cards, then discard a card.

Braineater Abominus can't be blocked by creatures with power 4 or greater.
Whenever a creature you control deals combat damage to a player, exile the top card of that player's library. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast it.

{1}{B}: Regenerate Brainless Ghoul. (The next time this creature would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)

If you would draw a card, instead exile the top three cards of your library face down. You may look at those cards. Put a card exiled with Brainstorming Session into its owner's hand.
{X}{X}{U}, Sacrifice Brainstorming Session: Put X cards exiled with it into their owner's hand.

Archive 5 (As this enters, shuffle the top five cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever a player discards a card, draw a card from the archived library.

[+2]: Discard a card at random. If you do, draw two cards.
[0]: Target creature's controller may pay X life. If they don't, you lose X life and gain control of it (Choose any number for X.)
[–3]: Flip a coin until you lose a flip or choose to stop flipping. For each flip you won, draw two cards and create a tapped Treasure token.

Enchant creature
When Bramble Armor enters, put a +1/+1 counter on enchanted creature.
{G}, Sacrifice Bramble Armor: Enchanted creature gains indestructible end of turn. Tap it.

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.