msem-instigator

For each creature token you control, create a token that's a copy of that creature.

Gain control of target nonland permanent you don't control unless its controller has Bow or Burn deal X damage to them, where X is twice that permanent's mana value. If Bow or Burn was cast from a graveyard, repeat this process for each other nonland permanent they control.
Flashback {6}{R}{R}

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

Counter target spell. Spells its controller casts cost {2} more to cast this turn.

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.

As Brave the Issbarrens enters, choose a color.
White creatures you control have protection from the chosen color. (This permanent can't be targeted, dealt damage, enchanted, or equipped by anything with that color.)

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.

Put a number of +1/+1 counters on target creature you control equal to that creature's power.
Spell mastery — If there are two or more instant or sorcery cards in your graveyard, you may have that creature fight another target creature. (Each deals damage equal to its power to the other.)

Double your life total. (Then exile this card. You may cast the creature later from exile.)

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

Hexproof
Whenever attackers are declared, the active player may pay {2} for each creature attacking you. Then you may have Bridge Kalak become an X/X Troll creature until end of turn, where X is the number of times that player didn't pay mana this way.

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

Flying, vigilance
Protection from Humans (This creature can't be blocked, targeted or dealt damage by Humans.)

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

Target player draws seven cards, then their life total becomes equal to the number of cards in their hand.

Distribute three +1/+1 counters among up to three target creatures you control. Those creatures gain first strike until end of turn.

Whenever you play a land, you may search your library for a land card that shares a subtype with it, put it onto the battlefield tapped, then shuffle.

When Broken Spirit enters, exile target creature an opponent controls until Broken Spirit leaves the battlefield.
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.)

{6}{U}: Brume Trench-Thrasher can't be blocked this turn. This ability costs {1} less to activate for each instant and sorcery card you own in exile and in your graveyard.

Ward {2}
Whenever Brunig enters or attacks, you may shuffle a card you own from outside the game into your library. If you do, you gain 2 life.
Brunig gets +2/+2 and has trample as long as your library contains at least forty cards more than the minimum deck size.

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

Choose target creature. Brutal Descent deals 2 damage to each creature other than the chosen creature.
Ferocious — If the chosen creature has power 4 or greater, Brutal Descent deals 4 damage to each creature other than the chosen creature instead.

Destroy target creature. Its controller discards a card.

Attacking creatures get +3/+0 until end of turn.

Whenever one or more creatures you control deal combat damage to a player, you may destroy target artifact or enchantment that player controls.
Whenever you cast a green creature spell, create a 3/3 green Wurm creature token with trample.