msem-instigator

Trample
Whenever Belligerent's Augur or another Warrior you control deals combat damage to a player, you may pay {1}{U}. If you do, draw a card.

Whenever Beragnian Brawlmaster or another Warrior you control enters, that Warrior fights target creature an opponent controls.
{R}{W}: Target Warrior creature gets +1/+1 until end of turn.

When Bessie's Brood enters, it fights target creature. (If there are no other creatures, it eats itself.)

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

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.

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.

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

Flying
When Blackblood Feaster enters, you may have each player sacrifice a creature.
Pay 2 life: Blackblood Feaster gets +2/+2 until end of turn. Activate only once each turn.

Flying, lifelink
Whenever Blackhearted Sphinx attacks, you may pay 3 life. If you do, draw a card.

At the beginning of combat on each of your turns, look at the top card of your library. You may put that card into your graveyard.
Whenever a land card is put into your graveyard from anywhere, each opponent loses 1 life and you gain 1 life.

Flash
When Blade of Mautakesh enters, creatures you control gain poisonous 1 until end of turn. (Whenever those creatures deal combat damage to a player, that player gets a poison counter. Multiple instances of poisonous trigger separately.)

Flying
Whenever Blade of Reckoning deals combat damage to a player, that player sacrifices an untapped permanent.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Advance {1}{R}{W}{B} (Cast this for {1}{R}{W}{B} to advance it as it enters. {1}{R}{W}{B}: Advance this as a sorcery.)
Whenever Blastburn Angel advances, it gets +1/+1 and gains flying until end of turn. It deals 1 damage to each other creature.

Haste
When Blighted Dullahan dies, you draw a card and you lose 1 life.

{1}{B}, {T}: Target creature gets +2/+2 and gains winnow until end of turn. (Damage dealt to it also causes its controller to lose that much life.)
{3}{B}{B}, {T}: Target creature gets -2/-2 and gains winnow until end of turn.

When Blighting Ooze enters, put a -1/-1 counter on each of up to X target creatures.
As long as Blighting Ooze is on the battlefield, it has all activated abilities of each creature with a -1/-1 counter on it.

Sacrifice a creature: Put a +1/+1 counter on Blightroot.
Sacrifice a land: Blightroot gains indestructible until end of turn.

Flash
Blind Blackguard can't block.
When Blind Blackguard enters, target player draws a card, then reveals their hand. You choose a nonland card from that player's hand, then that player puts the chosen card on the bottom of their library.

Vision (Whenever this or another creature you control enters, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Blind Soulcaller envisions an instant or sorcery card, you may tap target permanent.

Cycling {2} ({2}, Discard this card: Draw a card.)
{3}{B}{B}, Exile Bloated Visceroid from your graveyard: Create two 2/2 black Zombie creature tokens. Activate only as a sorcery.

When Blood Jade Prophet enters, reveal the top three cards of your library. For each card revealed this way, you may pay 3 life. If you do, put that card into your hand. Otherwise, put it into your graveyard.

Whenever you sacrifice a creature, you may pay {B}{G}. If you do, put a +1/+1 counter on Bloodblade Mercenary and draw a card.

Lionize {2}{R} ({2}{R}, Exile this card from your hand: Put a +1/+1 counter on target creature and it gains the following abilities until end of turn. You may cast this card on a later turn from exile.)
Trample
This creature gets +3/+0 as long as it's attacking.

Flying, menace, haste
When Bloodfiend Ravager enters, it deals 2 damage to any target. If a permanent dealt damage this way would die this turn, exile it instead.
Evoke {1}{R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)