Brainspoil

Destroy target creature that isn't enchanted. It can't be regenerated.
Transmute {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Kaya the Inexorable

+1: Put a ghostform counter on up to one target nontoken creature. It gains "When this creature dies or is put into exile, return it to its owner's hand and create a 1/1 white Spirit creature token with flying."
−3: Exile target nonland permanent.
−7: You get an emblem with "At the beginning of your upkeep, you may cast a legendary spell from your hand, from your graveyard, or from among cards you own in exile without paying its mana cost."

Dimir House Guard

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Sacrifice a creature: Regenerate Dimir House Guard.
Transmute {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Stinging Study

You draw X cards and you lose X life, where X is the mana value of a commander you own on the battlefield or in the command zone.

Piru, the Volatile

Flying, lifelink
At the beginning of your upkeep, sacrifice Piru, the Volatile unless you pay {R}{W}{B}.
When Piru dies, it deals 7 damage to each nonlegendary creature.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Seize the Spoils

As an additional cost to cast this spell, discard a card.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Pirate's Pillage

As an additional cost to cast this spell, discard a card.
Draw two cards and create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Rolling Earthquake

Rolling Earthquake deals X damage to each creature without horsemanship and each player.

Reckless Endeavor

Roll two d12 and choose one result. Reckless Endeavor deals damage equal to that result to each creature. Then create a number of Treasure tokens equal to the other result.

Painful Truths

Converge — You draw X cards and you lose X life, where X is the number of colors of mana spent to cast this spell.