Bruvac the Grandiloquent

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Altar of the Brood

Whenever another permanent you control enters, each opponent mills a card.

Belltower Sphinx

Flying
Whenever a source deals damage to Belltower Sphinx, that source's controller mills that many cards.

Feral Ghoul

Menace
Whenever another creature you control dies, put a +1/+1 counter on Feral Ghoul.
When Feral Ghoul dies, each opponent gets a number of rad counters equal to its power.

Radiation

At the beginning of your precombat main phase, if you have any rad counters, mill that many cards. For each nonland card milled this way, you lose 1 life and a rad counter.

Charmed Pendant

{T}, Mill a card: For each colored mana symbol in the milled card's mana cost, add one mana of that color. Activate only as an instant. (For example, if the card's mana cost is {3}{U}{U}{B}, you add {U}{U}{B}.)

Breach the Multiverse

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

The Wise Mothman

Flying
Whenever The Wise Mothman enters or attacks, each player gets a rad counter.
Whenever one or more nonland cards are milled, put a +1/+1 counter on each of up to X target creatures, where X is the number of nonland cards milled this way.

Bond of Insight

Each player mills four cards. Return up to two instant and/or sorcery cards from your graveyard to your hand. Exile Bond of Insight.

Armored Skaab

When Armored Skaab enters, mill four cards.

Blanchwood Prowler

When Blanchwood Prowler enters, mill three cards. You may put a land card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on Blanchwood Prowler. (To mill a card, put the top card of your library into your graveyard.)