Mutual Destruction

This spell has flash as long as you control a permanent with flash.
As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature.

Plains

Extinction Event

Choose odd or even. Exile each creature with mana value of the chosen quality. (Zero is even.)

Lurrus of the Dream-Den

Companion — Each permanent card in your starting deck has mana value 2 or less. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Lifelink
Once during each of your turns, you may cast a permanent spell with mana value 2 or less from your graveyard.

Swamp

Heartless Act

Choose one —
• Destroy target creature with no counters on it.
• Remove up to three counters from target creature.

Dead Weight

Enchant creature
Enchanted creature gets -2/-2.

Garrison Cat

When Garrison Cat dies, create a 1/1 white Human Soldier creature token.

Boot Nipper

Boot Nipper enters with your choice of a deathtouch counter or a lifelink counter on it.

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Call of the Death-Dweller

Return up to two target creature cards with total mana value 3 or less from your graveyard to the battlefield. Put a deathtouch counter on either of them. Then put a menace counter on either of them.

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Will of the All-Hunter

Target creature gets +2/+2 until end of turn. If it's blocking, instead put two +1/+1 counters on it.
Cycling {2} ({2}, Discard this card: Draw a card.)

Fiend Artisan

Fiend Artisan gets +1/+1 for each creature card in your graveyard.
{X}{B/G}, {T}, Sacrifice another creature: Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle. Activate only as a sorcery.