msem-instigator

When a creature you control becomes the target of a spell or ability an opponent controls, sacrifice Bestial Harmony. If you do, draw three cards.

Enchant creature
At the beginning of the upkeep of enchanted creature's controller, Betrayer's Mantle deals 3 damage to that player.

Whenever a creature card is put into your graveyard from the battlefield, exile it. You lose life equal to that card's mana value. Put it onto the battlefield tapped at the beginning of your next upkeep.

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.)

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

When Bjarndyr Militant enters, return target Aura card or card with fabled from your graveyard to your hand.

When Bjarndyr Outfitter enters, arm up to two target creatures you control. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

Lifelink
Whenever Bjarndyr Sergeant attacks, other creatures you control get +1/+1 and gain lifelink until end of turn.

Trample
Other Bears you control get +2/+2.

Nonbasic lands have “Whenever this land becomes tapped, you lose 1 life unless you sacrifice this land.”

Whenever equipped creature attacks, choose target creature defending player controls. Destroy that creature at end of combat.
Equip {4}

Equipped creature gets +1/+1 and has lifelink.
Whenever equipped creature dies, if it wasn't a token, you may pay {3}. If you do, create a token that's a copy of that creature and attach Bloodguard's Hand to it.
Equip {3}

Flash (You may cast this spell any time you could cast an instant.)
When Bloodhunter Orca enters, target opponent sacrifices a creature that was dealt damage this turn.

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

{T}: Another target Warrior you control gets +1/+0 and gains haste until end of turn.

Dominance — If you control the creature with the greatest power or tied for the greatest power, you may pay {U} rather than pay this spell's mana cost.
Counter target spell unless its controller pays {3}.

Trample
{T}: Add {C}.
At the beginning of your upkeep, you may pay {2}. When you do, Blundering Clocktower becomes a creature in addition to its other types until the beginning of your next end step. End the turn.

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

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.

When Braenid Nomad enters, draw two cards, then discard a card.

Target player discards two cards.
Fabled {3}{B}{B} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

Exile target creature. You gain 2 life.

Equipped creature has indestructible as long as it's your turn.
Whenever equipped creature attacks, it gets +X/+0 until end of turn, where X is its power.
Equip {6}

Whenever Bristled Wolverine attacks, it gets +1/+1 until end of turn.

Draw four cards, then untap up to two target lands.