msem-instigator

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

All creatures get -4/-4 until end of turn.

Legacy (You may play this side of this card only from your graveyard. Exile it if it would leave the battlefield or not resolve.)
Permanents you control have lifelink and “{T}: Add one mana of any color.”

Whenever a creature card is put into your graveyard from the battlefield, exile it. You lose life equal to that card's mana value. Put it onto the battlefield tapped at the beginning of your next upkeep.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Return target creature card from your graveyard to the battlefield. If it was put there from the battlefield this turn, create a token that's a copy of it. If you're in a renaissance, create a token that's a copy of it.

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.

Flying
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)
When Bitter Corvus enters, you may reveal the top X cards of your library, where X is Bitter Corvus' power. You may put up to one card revealed this way into your hand. You lose life equal to its mana value. Put the rest into your graveyard.

You may reveal a Knight or Soldier card from your hand as you cast this spell. If you do or you control one as you cast it, you may cast it as though it had flash and it can't be countered.
Exile target nonland permanent with mana value 3 or less.

At the beginning of your end step, mill two cards. Then if ten or more cards are in your graveyard, transform Bitter Duckling.

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.)

This spell can't be countered.
Whenever Bitter Leviathan becomes the target of a spell or ability, exile it. Return it to the battlefield under your control tapped and attacking at the beginning of the declare attackers step on your next turn. It can't be blocked that combat.

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

When Bitter Pact enters, destroy target nonbasic permanent.
All permanents and players lose hexproof, indestructible, and protection and can't have or gain hexproof, indestructible, or protection.

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

Return to your hand all permanent cards in your graveyard that were put there from the battlefield this turn.

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.)