msem-instigator

Armed — Beragnian Savage gets +1/+0 and has first strike as long as it's equipped.

When Bestower of Blooms dies, create an X/X green Plant Knight creature token, where X is Bestower of Blooms's power.

{T}, Exert Bestower of Princely Sin: You may sacrifice another creature. If you do, target opponent may sacrifice a permanent that shares a card type with it. If they don't, that player loses 1 life and you draw a card. Repeat this process for artifact, enchantment, land, and planeswalker. Activate only as a sorcery.

When Bezoarbeast dies, each opponent loses 2 life and you create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Trample, haste, indestructible
Whenever a permanent an opponent controls is put into a graveyard from the battlefield, put a +1/+1 counter on target Ooze.

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.

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

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

When Black Cat dies, target opponent discards a card at random.

Deathtouch
{B}, Pay 1 life: Add one mana of any color. Activate this ability only once each turn.

Whenever Blackfeather Cleric enters or attacks, exile target card from a graveyard. Put a +1/+1 counter on Blackfeather Cleric if it was a permanent card. Otherwise, you gain 1 life.
Surpass {5}{B} ({5}{B}: Transform this creature. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

When Blade of Reolem dies, target opponent discards a card at random.

Double strike
Attain {3}{R} ({3}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Poisonous 1 (Whenever this creature deals combat damage to a player, that player gets a poison counter.)
Blade of the Serpent gets +1/+1 as long as an opponent is poisoned.

Trample, haste
When Blazing Fox enters, you may tap an untapped creature you control. If you do, Blazing Fox gets +X/+0 until end of turn, where X is that creature's power.

Flying
When Bleak Condor enters, mill four cards.

{1}{G}, {T}: You may put a creature or Revelation card from your hand onto the battlefield. Exile that permanent if it would leave the battlefield. If it's a Revelation, it enters as a Horror creature and you may cast a copy of it without paying its mana cost.

Trample
{1}{G}: Put an overgrowth counter on target creature you control. As long as it has an overgrowth counter on it, it has base power and toughness 8/8.

Prowess

When Blisterbug dies, put two +1/+1 counters on target creature you control.

Advance {1}{R} (Cast this for {1}{R} to advance it as it enters. {1}{R}: Advance this as a sorcery.)
Whenever Blitz Breaker advances, its power becomes equal to the amount of noncombat damage that's been dealt to your opponents this turn. (This effect lasts indefinitely.)

Trample
{T}, Sacrifice another creature: You gain 3 life.
Whenever another creature you control dies, put a +1/+1 counter on Bloodbriar Archdruid.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Bloodied Twinblade dies, scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

{G}, {T}: Put a +1/+1 counter on Bloodleaf Tracker for each creature that entered this turn.

{1}, {T}, Pay 1 life: Put a +1/+1 counter on target creature you control.
{T}, Remove a counter from a permanent you control: Draw a card.