Ikoria: Lair of Behemoths

Mythos of Snapdax | Sorcery | | Each player chooses an artifact, a creature, an enchantment, and a planeswalker from among the nonland permanents they control, then sacrifices the rest. If {B}{R} was spent to cast this spell, you choose the permanents for each player instead. | Seb McKinnon

Mythos of Nethroi | Instant | | Destroy target nonland permanent if it's a creature or if {G}{W} was spent to cast this spell. | Seb McKinnon

Lurrus of the Dream-Den | Legendary Creature | Cat Nightmare | 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} any time you could cast a sorcery.) Lifelink During each of your turns, you may cast one permanent spell with mana value 2 or less from your graveyard. | Slawomir Maniak

Jegantha, the Wellspring | Legendary Creature | Elemental Elk | Companion — No card in your starting deck has more than one of the same mana symbol in its mana cost. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} any time you could cast a sorcery.) {T}: Add {W}{U}{B}{R}{G}. This mana can't be spent to pay generic mana costs. | Chris Rahn

Offspring's Revenge | Enchantment | | At the beginning of combat on your turn, exile target red, white, or black creature card from your graveyard. Create a token that's a copy of that card, except it's 1/1. It gains haste until your next turn. | Daarken

Ruinous Ultimatum | Sorcery | | Destroy all nonland permanents your opponents control. | Chase Stone

Death's Oasis | Enchantment | | Whenever a nontoken creature you control dies, mill two cards. Then return a creature card with lesser mana value than the creature that died from your graveyard to your hand. {1}, Sacrifice Death's Oasis: You gain life equal to the highest mana value among creatures you control. | Grzegorz Rutkowski

Eerie Ultimatum | Sorcery | | Return any number of permanent cards with different names from your graveyard to the battlefield. | Jason A. Engle

Indatha Triome | Land | Plains Swamp Forest | ({T}: Add {W}, {B}, or {G}.) Indatha Triome enters the battlefield tapped. Cycling {3} ({3}, Discard this card: Draw a card.) | Noah Bradley

Savai Triome | Land | Mountain Plains Swamp | ({T}: Add {R}, {W}, or {B}.) Savai Triome enters the battlefield tapped. Cycling {3} ({3}, Discard this card: Draw a card.) | Titus Lunter