Living Death

Each player exiles all creature cards from their graveyard, then sacrifices all creatures they control, then puts all cards they exiled this way onto the battlefield.

Alien Symbiosis

Enchant creature
Enchanted creature gets +1/+1, has menace, and is a Symbiote in addition to its other types.
You may cast this card from your graveyard by discarding a card in addition to paying its other costs.

Obsessive Stitcher

{T}: Draw a card, then discard a card.
{2}{U}{B}, {T}, Sacrifice this creature: Return target creature card from your graveyard to the battlefield.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Dread Return

Return target creature card from your graveyard to the battlefield.
Flashback—Sacrifice three creatures. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Symbiote Spider-Man

Whenever this creature deals combat damage to a player, look at that many cards from the top of your library. Put one of them into your hand and the rest into your graveyard.
Find New Host — {2}{U/B}, Exile this card from your graveyard: Put a +1/+1 counter on target creature you control. It gains this card's other abilities. Activate only as a sorcery.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to that card's mana value.

Stitch Together

Return target creature card from your graveyard to your hand.
Threshold — Return that card from your graveyard to the battlefield instead if there are seven or more cards in your graveyard.

The Ancient One

Descend 8 — The Ancient One can't attack or block unless there are eight or more permanent cards in your graveyard.
{2}{U}{B}: Draw a card, then discard a card. When you discard a card this way, target player mills cards equal to its mana value.