msem-instigator

When Bridled Narwhal enters the battlefield, you gain 5 life.

Deathtouch
When Brig of the Damned enters the battlefield, return target creature card from your graveyard to your hand. If that card's mana value is 2, you may return it to the battlefield instead.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Lifelink
When Bright-Eyed Adventurer enters the battlefield, rediscover an enchantment card. (Look at the top card of your library. You may reveal it and put it into your hand if it's an enchantment card. Otherwise, put it back or into your graveyard.)

Flash
When Brightsouled Guardian enters the battlefield, return up to one target nonland permanent to its owner's hand.

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

Defender
When Brine Duelist enters the battlefield, create a Treasure token. (It's an artifact with “{T}, Sacrifice this permanent: Add one mana of any color.”)
{W}{U}{B}{R}{G}: Put a +1/+1 counter on Brine Duelist. It loses defender.

Trample
When Bringer of Armies enters the battlefield, recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)

When Broadside Raider enters the battlefield, create a 1/1 blue and red Pirate creature token with haste.

When Broken Spirit enters the battlefield, 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.)

When Bubbledome Chorister enters the battlefield, create a green Aura enchantment token named Sanctum's Gift attached to target creature. The token has enchant creature and “Enchanted creature has ‘{T}: Add {G} for each enchanted creature you control.'”

When Bubblespout Sentry enters the battlefield, look at the top card of your library. You may put it into your graveyard.

When Bug Catcher enters the battlefield, create a 1/1 green Insect creature token.
Whenever a nontoken Insect you control dies, create a 1/1 green Insect creature token.

When Burglar Cat enters the battlefield, exile the top card of target opponent's library. You may play that card during any turn you attacked with a Rogue, and you may spend mana as though it were mana of any color to cast it.

When Bustling Bazaar enters the battlefield, return target artifact, instant, or sorcery card from your graveyard to your hand.
Sacrifice a nontoken artifact: Create two tapped Treasure tokens.

When Byron, Unlikely Hero enters the battlefield, put a +1/+1 counter on each other Citizen or Peasant you control.
Whenever a nontoken creature you control with a +1/+1 counter on it dies, create a 1/1 white Peasant creature token.

Flying
When Byte Bug enters the battlefield, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)

When Cadalon Experimenter enters the battlefield, if you control an artifact, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Flying
When Cadre Hawk enters the battlefield, you may search your library and/or graveyard for a card named Cadre Hawk, reveal it, and put it into your hand. If you searched a library this way, shuffle.

When Caer Crann Borderscout enters the battlefield, you may search your library for a basic land card, reveal it, and put it into your hand. If you do, shuffle.

When Caer Crann Warleader enters the battlefield, distribute three +1/+1 counters among any number of creatures you control.
Embattled creatures you control have trample. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Enchant creature
When Cage the Dissenter enters the battlefield, scry 2.
Enchanted creature doesn't untap during its controller's untap step.

Flying
When Calamity Dragon enters the battlefield, it deals 2 damage to each creature you don't control. Whenever a creature dealt damage this way dies this turn, Calamity Dragon deals 2 damage to that creature's controller.

Flying
When Calamity Harbinger enters the battlefield, it deals 4 damage to up to one target creature or planeswalker.

When Calamity Rose enters the battlefield, each player chooses a number of artifacts they control equal to the number of artifacts controlled by the player who controls the fewest, then sacrifices the rest. Players sacrifice creatures, enchantments, lands and planeswalkers the same way.

When Callous Renegade enters the battlefield, you may return target Rebel creature card with mana value 4 or less from your graveyard to the battlefield. It gains haste until end of turn.