msem-instigator

At the beginning of each player's end step, if they aren't horrific, Bloody Valentine deals 2 damage to that player. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

For each Aura you control, create a token that's a copy of that Aura.

You may have Blurry Counterpart enter as a copy of any creature on the battlefield.
Mirage {1}{U} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Target creature gets +2/+2 until end of turn.
Fuse (You may cast one or both halves of this card from your hand.)

Whenever another creature you control enters, you may have it gain haste. If you do, return it to its owner's hand at the beginning of the next end step.

Menace
When Bogborn Exorcist enters, you may discard a card. When you do, exile target instant or sorcery card with mana value 3 or less from an opponent's graveyard. Copy that card. You may cast the copy without paying its mana cost.

At the beginning of your upkeep, you may pay 3 life. If you do, create a 2/1 red Lizard creature token with frenzy 2. (Whenever it attacks and isn't blocked, it gets +2/+0 until end of turn.)

Each creature you control gets +1/+1 for each permanent attached to it.

Damage can't be prevented.
At the beginning of your upkeep, Bomb Juggler deals 3 damage to target player chosen at random.

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

At the beginning of your upkeep, sacrifice a non-Snake creature or Boon of the Pacts. Then create a 1/1 black Snake creature token with deathtouch.
At the beginning of your draw step, draw an additional card.
Spells you cast cost {1} less to cast.

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.

Your life total becomes 20.
Coalesce {8}{W}{W}{W}{W} (You may cast this from your graveyard for {8}{W}{W}{W}{W}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Born Anew's power and toughness are each equal to your life total.

Whenever a creature you control deals combat damage to a player, you may sacrifice it. If you do, draw cards equal to that creature's power.

Eureka! (At the beginning of each end step, you get a research counter if you cast a spell this turn. Then if you have eight or more research counters, remove them and create a Masterpiece token of your choice.)
When Bottled Lightning enters, it deals 3 damage to any target. Scry 1.

For each creature token you control, create a token that's a copy of that creature.

{B}, {T}: Post a bounty on target permanent. (Put a bounty counter on that permanent. It has “When this permanent is put into a graveyard from the battlefield, each opponent draws a card” as long as it has a bounty counter on it.)
{B}, {T}, Pay 2 life: Destroy target creature with a bounty counter on it.

If you would draw a card, instead exile the top three cards of your library face down. You may look at those cards. Put a card exiled with Brainstorming Session into its owner's hand.
{X}{X}{U}, Sacrifice Brainstorming Session: Put X cards exiled with it into their owner's hand.

Gain control of target permanent. (Cast a copy of this spell once while this creature is on the battlefield.)

Archive 5 (As this enters, shuffle the top five cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever a player discards a card, draw a card from the archived library.

[+2]: Discard a card at random. If you do, draw two cards.
[0]: Target creature's controller may pay X life. If they don't, you lose X life and gain control of it (Choose any number for X.)
[–3]: Flip a coin until you lose a flip or choose to stop flipping. For each flip you won, draw two cards and create a tapped Treasure token.

First strike
Whenever you cast an instant or sorcery spell, if Branch Breaker dealt combat damage to a player this turn, you may sacrifice Branch Breaker. If you do, copy that spell. You may choose new targets for the copy.

Sacrifice another creature: Brash Hunter deals 1 damage to any target.
At the beginning of your end step, if three or more creatures died this turn, transform Brash Hunter.

As Brave the Issbarrens enters, choose a color.
White creatures you control have protection from the chosen color. (This permanent can't be targeted, dealt damage, enchanted, or equipped by anything with that color.)

Double strike
{1}{R}{W}: Target creature gains double strike until end of turn. Activate only if Bravery is in your graveyard.