Patchwork Beastie

Delirium — Patchwork Beastie can't attack or block unless there are four or more card types among cards in your graveyard.
At the beginning of your upkeep, you may mill a card. (You may put the top card of your library into your graveyard.)

Gutterbones

Gutterbones enters tapped.
{1}{B}: Return Gutterbones from your graveyard to your hand. Activate only during your turn and only if an opponent lost life this turn.

Cult Conscript

Cult Conscript enters tapped.
{1}{B}: Return Cult Conscript from your graveyard to the battlefield. Activate only if a non-Skeleton creature died under your control this turn.

Oathsworn Vampire

Oathsworn Vampire enters tapped.
You may cast Oathsworn Vampire from your graveyard if you gained life this turn.

Putrid Imp

Discard a card: Putrid Imp gains flying until end of turn.
Threshold — As long as seven or more cards are in your graveyard, Putrid Imp gets +1/+1 and can't block.

Persist

Return target nonlegendary creature card from your graveyard to the battlefield with a -1/-1 counter on it.

Leonin Squire

When Leonin Squire enters, return target artifact card with mana value 1 or less from your graveyard to your hand.

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.)

Golgari Thug

When Golgari Thug dies, put target creature card from your graveyard on top of your library.
Dredge 4 (If you would draw a card, you may mill four cards instead. If you do, return this card from your graveyard to your hand.)

Treasure Cruise

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Draw three cards.

Narcomoeba

Flying
When Narcomoeba is put into your graveyard from your library, you may put it onto the battlefield.

Gollum, Patient Plotter

When Gollum, Patient Plotter leaves the battlefield, the Ring tempts you.
{B}, Sacrifice a creature: Return Gollum from your graveyard to your hand. Activate only as a sorcery.

Aftermath Analyst

When Aftermath Analyst enters, mill three cards.
{3}{G}, Sacrifice Aftermath Analyst: Return all land cards from your graveyard to the battlefield tapped.

Rubblebelt Maverick

When Rubblebelt Maverick enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{G}, Exile Rubblebelt Maverick from your graveyard: Put a +1/+1 counter on target creature. Activate only as a sorcery.

Gitaxian Probe

({U/P} can be paid with either {U} or 2 life.)
Look at target player's hand.
Draw a card.

Nimble Mongoose

Shroud (This creature can't be the target of spells or abilities.)
Threshold — Nimble Mongoose gets +2/+2 as long as seven or more cards are in your graveyard.

Myr Servitor

At the beginning of your upkeep, if Myr Servitor is on the battlefield, each player returns all cards named Myr Servitor from their graveyard to the battlefield.

Golgari Grave-Troll

Golgari Grave-Troll enters with a +1/+1 counter on it for each creature card in your graveyard.
{1}, Remove a +1/+1 counter from Golgari Grave-Troll: Regenerate Golgari Grave-Troll.
Dredge 6 (If you would draw a card, you may mill six cards instead. If you do, return this card from your graveyard to your hand.)

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Doc Aurlock, Grizzled Genius

Spells you cast from your graveyard or from exile cost {2} less to cast.
Plotting cards from your hand costs {2} less.

Dragon's Rage Channeler

Whenever you cast a noncreature spell, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
Delirium — As long as there are four or more card types among cards in your graveyard, Dragon's Rage Channeler gets +2/+2, has flying, and attacks each combat if able.