Merchant of Venom

Menace
When this creature enters, each player sacrifices a creature of their choice.
Whenever a player sacrifices a permanent, put a +1/+1 counter on this creature.

Ominous Harvest

Gravestorm (When you cast this spell, copy it for each permanent put into a graveyard from the battlefield this turn.)
Target player draws a card and loses 1 life.

Stensian Sanguinist

Whenever you attack, target creature gains deathtouch until end of turn. Whenever that creature deals combat damage to a player this combat, this creature becomes prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Stensian Sanguinist // Exsanguinate

Fateful Tempest

Council's dilemma — Starting with you, each player votes for past or present. You mill a card for each past vote, then Fateful Tempest deals damage to each opponent equal to the total mana value of cards milled this way. Exile the top card of your library for each present vote. Until the end of your next turn, you may play the exiled cards.

Rootha, Mastering the Moment

Elemental

At the beginning of combat on your turn, if you've cast an instant or sorcery spell this turn, create an X/X blue and red Elemental creature token with flying and haste, where X is the greatest mana value among instant and sorcery spells you've cast this turn.

Furygale Flocking

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
For each opponent, create two 3/3 blue and red Elemental creature tokens with flying that attack that opponent this turn if able. They gain haste until end of turn.

Naktamun Lorespinner

At the beginning of your upkeep, if a player has one or fewer cards in hand, this creature becomes prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Wheel of Fortune

Each player discards their hand, then draws seven cards.

Naktamun Lorespinner // Wheel of Fortune

Prismari Pianist

Whenever you cast an instant or sorcery spell, create a 1/1 blue and red Elemental creature token. If that spell's mana value is 5 or greater, create three of those tokens instead.

Treasure

Relic Retriever

First strike
At the beginning of each end step, if a card left your graveyard this turn, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Renegade Bull

Trample
Whenever you cast an instant or sorcery spell, this creature gets +X/+0 until end of turn, where X is that spell's mana value.
Whenever this creature attacks, exile up to one target instant or sorcery card from your graveyard and copy it. You may cast the copy without paying its mana cost.

Spirit of Resilience

Whenever one or more cards leave your graveyard, put a +1/+1 counter on this creature, then you may have this creature become a copy of an artifact or creature card from among those cards until end of turn.

Pest

Feral Appetite

Attacking Pests you control get +1/+0 and have deathtouch.
{1}{G}: Exile target card from a graveyard. If a creature card is exiled this way, create a 1/1 black and green Pest creature token with "When this token dies, you gain 1 life."

Kinetic Ooze

This creature enters with X +1/+1 counters on it.
When this creature enters, destroy up to one target artifact or enchantment with mana value X or less. If X is 5 or more, you draw a card. If X is 10 or more, double the number of +1/+1 counters on any number of other target creatures.

Lattice Library

Fractal

This enchantment enters with X study counters on it.
When this enchantment enters and whenever you cast your first spell with {X} in its mana cost each turn, create a 0/0 green and blue Fractal creature token. Put a number of +1/+1 counters on it equal to the number of study counters on this enchantment.

Nev, the Practical Dean

Creatures you control with counters on them have trample.
Whenever you cast your first spell with {X} in its mana cost each turn, put X +1/+1 counters on Nev.

Scriv, the Obligator

Contract

Flying, deathtouch
Whenever Scriv enters or attacks, create a white Aura enchantment token named Contract attached to target creature an opponent controls. The token has enchant creature and "Whenever enchanted creature attacks, it gets +2/+0 until end of turn if it's attacking one of your opponents. Otherwise, its controller loses 2 life."

Secrets of Strixhaven Commander