Lazav, Familiar Stranger

Whenever you commit a crime, put a +1/+1 counter on Lazav, Familiar Stranger. Then you may exile a card from a graveyard. If a creature card was exiled this way, you may have Lazav become a copy of that card until end of turn. This ability triggers only once each turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Codex Shredder

{T}: Target player mills a card. (They put the top card of their library into their graveyard.)
{5}, {T}, Sacrifice Codex Shredder: Return target card from your graveyard to your hand.

Tinybones Joins Up

When Tinybones Joins Up enters the battlefield, any number of target players each discard a card.
Whenever a legendary creature enters the battlefield under your control, any number of target players each mill a card and lose 1 life.

Thought Scour

Target player mills two cards.
Draw a card.

Jace's Erasure

Whenever you draw a card, you may have target player mill a card.

Counterspell

Glimpse the Unthinkable

Drown in the Loch

Choose one —
• Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard.
• Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.

Hedron Crab

Landfall — Whenever a land enters the battlefield under your control, target player mills three cards.

Tinybones, the Pickpocket

Deathtouch
Whenever Tinybones, the Pickpocket deals combat damage to a player, you may cast target nonland permanent card from that player's graveyard, and mana of any type can be spent to cast that spell.

Ruin Crab

Landfall — Whenever a land enters the battlefield under your control, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Soured Springs

Soured Springs enters the battlefield tapped.
When Soured Springs enters the battlefield, it deals 1 damage to target opponent.
{T}: Add {U} or {B}.