msem-instigator

When Bio-Sequencer enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
{1}, {T}, Sacrifice Bio-Sequencer: Add one mana of any color.

{T}: Add one mana of any color a basic land you control could produce.

Enchant creature
Enchanted creature gets +2/+2 and has lifelink.

Return up to one target spell to its owner's hand.
Create two 1/1 blue Elemental creature tokens with flying. They can't block this turn.

When Bioluminescent Predator dies, draw a card, then you may put a land card from your hand onto the battlefield.

When Bird Call enters, search your library for a creature card, reveal it, shuffle, then put that card on top.
{2}, {T}: Target creature gets +1/+1 until end of turn.

Lifelink
At the beginning of your end step, if you've gained 3 or more life this turn, create a 2/2 white Bird creature token with flying.

Flying
Bird of Many Feathers can block only creatures with flying.
Whenever you scry, put a +1/+1 counter on Bird of Many Feathers.

Create a 1/1 blue Bird creature token with flying, then put the bottom card of your library into your hand.

Create a 1/1 blue Bird creature token with flying. (Cast a copy of this spell once while this creature is on the battlefield.)

Whenever Birthing Elemental or another nontoken creature you control dies, create a 1/1 green Saproling creature token.

Lifelink
When Birthright Proselyte enters, return target permanent card with mana value 2 or less from your graveyard to the battlefield.

Menace
When Bit Player dies, it deals 1 damage to each opponent.

Destroy target creature with flying.

Target opponent exiles a card from their hand. If this spell was cast from a graveyard, instead look at that player's hand, you choose a nonland card from it, then exile that card.
Flashback {2}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Target player discards a card. Return a creature card from your graveyard to your hand.

Target opponent reveals their hand. You choose an instant or sorcery card from it or a card from their graveyard. Exile that card.

Whenever you put one or more -1/-1 counters on a creature, create that many 1/1 black Faerie creature tokens with flying.

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Bitter Wanderer desecrates a permanent, each opponent loses 2 life and you gain 2 life.

Deathtouch
When Bitterheart Bokor leaves the battlefield, you may search your library for a Curse card, reveal it, put it into your hand, then shuffle.

You gain 2 life. Then if you have more life than an opponent, draw a card.
At the beginning of your upkeep, if Bittersweet Reunion is in your graveyard, you may pay {1}{W} and exile it. If you do, you may copy it and cast the copy without paying its mana cost.

At the beginning of your upkeep, exile the top card of your library. If a land card is exiled this way, add {R}{R}. You don't lose this mana as steps and phases end this turn. Otherwise, you may cast that card this turn.

When Bizarre Dreams enters, destroy up to one target artifact or enchantment.
{3}{W}, Sacrifice Bizarre Dreams: Create two 1/1 blue Elemental creature tokens with flying. They can't block this turn.

Bjarndyr Bruiser gets +2/+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.)

When Bjarndyr Mender enters, other creatures you control get +1/+1 and gain indestructible until end of turn.