msem-instigator

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.)

{1}, Sacrifice Brackwater Scuttler: Draw a card.

{1}{B}: Regenerate Brainless Ghoul. (The next time this creature would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)

Enchant creature
When Bramble Armor enters, put a +1/+1 counter on enchanted creature.
{G}, Sacrifice Bramble Armor: Enchanted creature gains indestructible end of turn. Tap it.

{5}: Brass Dragon gets +3/+0 and gains flying and first strike until end of turn.

Enchant creature
Enchanted creature gets +2/+2 as long as it's an Actor. Otherwise, it gets -2/-2.

Flying

Foretell {1}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Brimstone Oration deals 2 damage to any target. If this spell was foretold, it deals 4 damage to any target instead.

Broken Deathbringer gets +1/+0 as long as you have 10 or less life.
Broken Deathbringer gets +1/+0 as long as there are one or fewer cards in your hand.

Target creature gets +0/+3 until end of turn. Whenever that creature perseveres this turn, draw a card. (A creature perseveres when it survives damage.)

Whenever a creature you control becomes the target of a spell or ability, counter it unless its controller pays {1}. Whenever they do, put a +1/+1 counter on Brushcover Elf. (This includes your spells and abilities.)

Destroy target artifact.
Reprise {R} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)

Target creature gets +3/+3 until end of turn.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Concord — As long as there are four or more card types among permanents you control, Bubbledome Waveblade gets +1/+1.

Target creature gets +2/+2 until end of turn. If it's an artifact creature, it gains indestructible until end of turn.

Target attacking creature gets +3/+3 until end of turn. If it's an artifact creature, it gains trample until end of turn.

{T}, Sacrifice a creature: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
{T}, Sacrifice a Clue: Create a 3/3 green Elemental creature token.

Target creature gets +2/+0 and gains haste until end of turn.
Flashback {1}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Target creature or planeswalker you control explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 or loyalty counter on that permanent, then you may put that card into your graveyard.)

Create a 1/1 colorless Construct Actor creature token. Put a +1/+1 counter on it if you control another Construct.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Exile target nontoken creature. That creature's controller creates X 1/1 red and white Warrior creature tokens, where X is that creature's mana value.

First strike
Whenever you make first contact, Callous Conduit deals 1 damage to target player or planeswalker. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Archive 3 (As this enters, shuffle the top three cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, put the top card of your main library on the bottom of the archived library.
{G}: Exchange a card from the archived library with a card from your hand.

{T}, Sacrifice Camahueto Calf: Return target land card from your graveyard to the battlefield.

Enchant creature you control
Enchanted creature gets +1/+1 and has ward {1}.
Whenever enchanted creature deals combat damage to a player, choose target creature you control without a permanent named Candlegift attached to it. Create a token that's a copy of Candlegift attached to that creature.
{W}, Sacrifice five enchantments: Create a 5/5 white Angel creature token with flying.