msem-instigator

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Sacrifice Bonetooth Darter: Counter target instant, planeswalker, or sorcery spell unless its controller pays {1}.

You may pay {1}{B} and tap an untapped Shaman you control rather than pay this spell's mana cost.
Target player sacrifices a creature. You gain life equal to its toughness.

When Boneweary Warrior dies, you may put a -1/-1 counter on target creature.

Deathtouch

Boneyard Pass enters tapped unless you control a basic land.
{T}: Add {W} or {B}.

This spell costs {2} less to cast if you control a creature with power 4 or greater.
Bonk deals 4 damage to any target.

Return target nonland permanent you control and target nonland permanent you don't control to their owners' hands.

If casting this spell causes a triggered ability of its target to trigger, that ability triggers an additional time.
Target creature gains first strike until end of turn.

When Border Seeker dies, search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then you gain 1 life for each land you control.

When Borderland Garrison enters, it deals 1 damage to up to one target creature and 1 damage to you.

Choose one—
• Manifest target creature card from your graveyard. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
• Return up to two target creature cards from your graveyard to your hand.

{G}, {T}, Remove a +1/+1 counter from a creature you control: Create a 2/2 green Ox creature token.

Assault {R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Borsuppa Outrider assaults, it deals 2 damage to each opponent.

Whenever Borsuppa Roughrider attacks, create a colorless Desert land token named Scoured Path with “{T}: Add {R}.” Sacrifice that token at the beginning of the next end step.

Menace (This creature can't be blocked except by two or more creatures.)
Assault {R} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)

{2}, Sacrifice Bottled Fate: Put the top card and bottom card of your library into your hand.

Whenever Bound Apparition becomes the target of a spell or ability, put a -1/-1 counter on it.

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

When Boundary Hallowblade enters, create a white Aura enchantment token named Consecration Blessing attached to target land. The token has enchant land and “Enchanted land is named Hallowed Ground and has indestructible.”

You may cast a spell with mana value 3 or less from your hand without paying its mana cost. (Then exile this card. You may cast the creature later from exile.)

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.

Whenever a creature with a counter on it dies, create a Gold token. (It's an artifact with “Sacrifice this artifact: Add one mana of any color.”)

Create an X/X green and blue Plant creature token, where X is the number of differently named lands you control.

Harmony — Create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”
When Bouquet Singer enters, harmonize. (Trigger up to one harmony of one permanent you control.)