Crab Umbra

Enchant creature
{2}{U}: Untap enchanted creature.
Totem armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Nihil Spellbomb

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard.
When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Caustic Caterpillar

{1}{G}, Sacrifice Caustic Caterpillar: Destroy target artifact or enchantment.

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Ooze Garden

{1}{G}, Sacrifice a non-Ooze creature: Create an X/X green Ooze creature token, where X is the sacrificed creature's power. Activate only as a sorcery.

Doomsday

Search your library and graveyard for five cards and exile the rest. Put the chosen cards on top of your library in any order. You lose half your life, rounded up.

Plaguecrafter

When Plaguecrafter enters the battlefield, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Seal of Removal

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Muldrotha, the Gravetide

During each of your turns, you may play a land and cast a permanent spell of each permanent type from your graveyard. (If a card has multiple permanent types, choose one as you play it.)

Torment of Hailfire

Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent or discards a card.

The Eldest Reborn

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Each opponent sacrifices a creature or planeswalker.
II — Each opponent discards a card.
III — Put target creature or planeswalker card from a graveyard onto the battlefield under your control.

Pattern of Rebirth

Enchant creature
When enchanted creature dies, that creature's controller may search their library for a creature card, put that card onto the battlefield, then shuffle.

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

Seal of Doom

Sacrifice Seal of Doom: Destroy target nonblack creature. It can't be regenerated.

Vessel of Nascency

{1}{G}, Sacrifice Vessel of Nascency: Reveal the top four cards of your library. You may put an artifact, creature, enchantment, land, or planeswalker card from among them into your hand. Put the rest into your graveyard.

Villainous Wealth

Target opponent exiles the top X cards of their library. You may cast any number of spells with mana value X or less from among them without paying their mana costs.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Sylvan Scrying

Search your library for a land card, reveal it, put it into your hand, then shuffle.

Victimize

Choose two target creature cards in your graveyard. Sacrifice a creature. If you do, return the chosen cards to the battlefield tapped.

Archaeomancer

When Archaeomancer enters the battlefield, return target instant or sorcery card from your graveyard to your hand.

Spider Umbra

Enchant creature
Enchanted creature gets +1/+1 and has reach. (It can block creatures with flying.)
Totem armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Secrets of the Dead

Whenever you cast a spell from your graveyard, draw a card.

Protean Hulk

When Protean Hulk dies, search your library for any number of creature cards with total mana value 6 or less, put them onto the battlefield, then shuffle.

Buried Alive

Search your library for up to three creature cards, put them into your graveyard, then shuffle.

Seal of Primordium

Sacrifice Seal of Primordium: Destroy target artifact or enchantment.

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Izoni, Thousand-Eyed

Undergrowth — When Izoni, Thousand-Eyed enters the battlefield, create a 1/1 black and green Insect creature token for each creature card in your graveyard.
{B}{G}, Sacrifice another creature: You gain 1 life and draw a card.