Space-Time Anomaly

Target player mills cards equal to your life total.

It'll Quench Ya!

Counter target spell unless its controller pays {2}.

Yue, the Moon Spirit

Flying, vigilance
Waterbend {5}, {T}: You may cast a noncreature spell from your hand without paying its mana cost.

Island

Octopus Form

Target creature you control gets +1/+1 and gains hexproof until end of turn. Untap it. (It can't be the target of spells or abilities your opponents control.)

Master Pakku

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever Master Pakku becomes tapped, target player mills X cards, where X is the number of Lesson cards in your graveyard. (They put the top X cards of their library into their graveyard.)

Boomerang Basics

Return target nonland permanent to its owner's hand. If you controlled that permanent, draw a card.

The Mindskinner

The Mindskinner can't be blocked.
If a source you control would deal damage to an opponent, prevent that damage and each opponent mills that many cards.

Crashing Wave

As an additional cost to cast this spell, waterbend {X}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
Tap up to X target creatures, then distribute three stun counters among tapped creatures your opponents control. (If a permanent with a stun counter would become untapped, remove one from it instead.)

The Water Crystal

Blue spells you cast cost {1} less to cast.
If an opponent would mill one or more cards, they mill that many cards plus four instead.
{4}{U}{U}, {T}: Each opponent mills cards equal to the number of cards in your hand.

University Campus

This land enters tapped.
{T}: Add {W} or {U}.
{4}, {T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

North Pole Patrol

{T}: Untap another target permanent you control.
Waterbend {3}, {T}: Tap target creature an opponent controls. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

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.)