msem-instigator

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.)

Trample

Trample
Revive {5}{B} ({5}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

When Blightbringer enters, creatures your opponents control get -1/-1 until end of turn.
Unearth {3}{B} ({3}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

{4}{R}: Blind Tunneler gets +3/+0 until end of turn.

Flying
Whenever Blizzard Dragon attacks, tap an artifact, a creature, and a land defending player controls. They don't untap during their controller's next untap step.
At the beginning of each opponent's upkeep, that player sacrifices a tapped permanent.

Whenever Blood Constrictor becomes blocked by a creature, you gain life equal to that creature's toughness.

Improve {1}{R} ({1}{R}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
As long as Bloodbelly Glutton is embattled, it has first strike, menace, and haste. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Haste
Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Bloodboil Harlequin desecrates a permanent, up to two target creatures can't block this turn.

Sacrifice another creature: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
When Bloodchill Risen enters, if it engorged an instant card, return target creature to its owner's hand.

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)

Flying
{1}, Sacrifice another creature: Regenerate target Vampire.

Other Warriors you control get +2/+0.
Whenever a Warrior you control dies, Bloodshed Devotee deals 1 damage to target opponent.

Discard a card: Bloodshot Berserker gets +1/-1 until end of turn. Any player may activate this ability.

Whenever a creature dies, put a +1/+1 counter on Bog Apex.

Whenever Boghex Witch deals combat damage to a cursed player, that player loses the game.
{2}{B}: Look at the top five cards of your library. You may reveal a Curse card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Whenever Bold Vanquisher attacks, upgrade it. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Trample

Vigilance, deathtouch
Civilized — When Bordermakers enters, if you control a creature, an artifact, and an enchantment, each opponent loses 4 life and you gain 4 life.

Flying
Whenever you attack, another target creature you control gains flying until end of turn.
Fleeting {U} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Bounty Crusher has trample as long as it's being blocked by a marked creature.

When Bridled Narwhal enters, you gain 5 life.

Deathtouch
When Brig of the Damned enters, 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.)

Defender
When Brine Duelist enters, 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, recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)