Riverchurn Monument

{1}, {T}: Any number of target players each mill two cards. (Each of them puts the top two cards of their library into their graveyard.)
Exhaust — {2}{U}{U}, {T}: Any number of target players each mill cards equal to the number of cards in their graveyard. (Activate each exhaust ability only once.)

Teval's Judgment

Whenever one or more cards leave your graveyard, choose one that hasn't been chosen this turn —
• Draw a card.
• Create a Treasure token.
• Create a 2/2 black Zombie Druid creature token.

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards. (They put the top three cards of their library into their graveyard.)

Afterlife from the Loam

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
For each player, choose up to one target creature card in that player's graveyard. Put those cards onto the battlefield under your control. They're Zombies in addition to their other types.

Treasure Cruise

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

River Kelpie

Whenever this creature or another permanent enters from a graveyard, draw a card.
Whenever a player casts a spell from a graveyard, draw a card.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Essence Anchor

At the beginning of your upkeep, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Create a 2/2 black Zombie Druid creature token. Activate only during your turn and only if a card left your graveyard this turn.

Life from the Loam

Return up to three target land cards from your graveyard to your hand.
Dredge 3 (If you would draw a card, you may mill three cards instead. If you do, return this card from your graveyard to your hand.)

Teval, the Balanced Scale

Flying
Whenever Teval attacks, mill three cards. Then you may return a land card from your graveyard to the battlefield tapped.
Whenever one or more cards leave your graveyard, create a 2/2 black Zombie Druid creature token.

Diviner of Mist

Flying
Whenever this creature attacks, mill four cards. You may cast an instant or sorcery spell from your graveyard with mana value 4 or less without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Welcome the Dead

Draw two cards, then discard a card and you lose 2 life. Create X tapped 2/2 black Zombie Druid creature tokens, where X is the number of cards that were put into your graveyard from your hand or library this turn.
Flashback {5}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Teval, Arbiter of Virtue

Flying, lifelink
Spells you cast have delve. (Each card you exile from your graveyard while casting those spells pays for {1}.)
Whenever you cast a spell, you lose life equal to its mana value.