Tideforce Elemental

{U}, {T}: You may tap or untap another target creature.
Landfall — Whenever a land you control enters, you may untap Tideforce Elemental.

Waterknot

Enchant creature
When Waterknot enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Time of Ice

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Tap target creature an opponent controls. It doesn't untap during its controller's untap step for as long as you control Time of Ice.
III — Return all tapped creatures to their owners' hands.

Rhythmic Water Vortex

Return up to two target creatures to their owner's hand.
Search your library and/or graveyard for a card named Mu Yanling, reveal it, and put it into your hand. If you searched your library this way, shuffle.

Rush of Ice

Tap target creature. It doesn't untap during its controller's next untap step.
Awaken 3—{4}{U} (If you cast this spell for {4}{U}, also put three +1/+1 counters on target land you control and it becomes a 0/0 Elemental creature with haste. It's still a land.)

Iceberg

Iceberg enters with X ice counters on it.
{3}: Put an ice counter on Iceberg.
Remove an ice counter from Iceberg: Add {C}.

Aetherspouts

For each attacking creature, its owner puts it on their choice of the top or bottom of their library.

Devastation Tide

Return all nonland permanents to their owners' hands.
Miracle {1}{U} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Ice Cage

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated.
When enchanted creature becomes the target of a spell or ability, destroy Ice Cage.

Drawn from Dreams

Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in a random order.

Roiling Waters

Return up to two target creatures your opponents control to their owners' hands. Target player draws two cards.

Eel Umbra

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Sanctum of Calm Waters

At the beginning of your first main phase, you may draw X cards, where X is the number of Shrines you control. If you do, discard a card.

Encase in Ice

Flash (You may cast this spell any time you could cast an instant.)
Enchant red or green creature
When Encase in Ice enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Rage of Winter

Tap target creature. It doesn't untap during its controller's next untap step. (Then exile this card. You may cast the creature later from exile.)

Queen of Ice

Whenever Queen of Ice deals combat damage to a creature, tap that creature. It doesn't untap during its controller's next untap step.

Queen of Ice // Rage of Winter

Tidespout Tyrant

Flying
Whenever you cast a spell, return target permanent to its owner's hand.

Tidal Wave

Create a 5/5 blue Wall creature token with defender. Sacrifice it at the beginning of the next end step.

Griptide

Put target creature on top of its owner's library.

Chilling Trap

Target creature gets -4/-0 until end of turn. If you control a Wizard, draw a card.

Dreadwaters

Target player mills X cards, where X is the number of lands you control.

Coastal Breach

Undaunted (This spell costs {1} less to cast for each opponent.)
Return all nonland permanents to their owners' hands.

Wall of Water

Defender (This creature can't attack.)
{U}: Wall of Water gets +1/+0 until end of turn.

Drown in Shapelessness

Return target creature to its owner's hand.

Read the Tides

Choose one —
• Draw three cards.
• Return up to two target creatures to their owners' hands.

Hydromorph Guardian

{U}, Sacrifice Hydromorph Guardian: Counter target spell that targets a creature you control.

Water Servant

{U}: Water Servant gets +1/-1 until end of turn.
{U}: Water Servant gets -1/+1 until end of turn.

Ice Over

Enchant artifact or creature
Enchanted permanent doesn't untap during its controller's untap step.

Uncomfortable Chill

Creatures your opponents control get -2/-0 until end of turn.
Draw a card.

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Floodhound

{3}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Icy Blast

Tap X target creatures.
Ferocious — If you control a creature with power 4 or greater, those creatures don't untap during their controllers' next untap steps.

Flooded Shoreline

{U}{U}, Return two Islands you control to their owner's hand: Return target creature to its owner's hand.

Floodwaters

Return up to two target creatures to their owners' hands.
Cycling {2} ({2}, Discard this card: Draw a card.)

Part Water

X target creatures gain islandwalk until end of turn. (They can't be blocked as long as defending player controls an Island.)

Flood of Tears

Return all nonland permanents to their owners' hands. If you return four or more nontoken permanents you control this way, you may put a permanent card from your hand onto the battlefield.

Tidal Surge

Tap up to three target creatures without flying.

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Tidal Force

At the beginning of each upkeep, you may tap or untap target permanent.

Chilling Grasp

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.
Madness {3}{U} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Lier, Disciple of the Drowned

Spells can't be countered.
Each instant and sorcery card in your graveyard has flashback. The flashback cost is equal to that card's mana cost.

Tide Shaper

Kicker {1} (You may pay an additional {1} as you cast this spell.)
When Tide Shaper enters, if it was kicked, target land becomes an Island for as long as Tide Shaper remains on the battlefield.
Tide Shaper gets +1/+1 as long as an opponent controls an Island.

Displacement Wave

Return all nonland permanents with mana value X or less to their owners' hands.

Crashing Tide

This spell has flash as long as you control a Merfolk.
Return target creature to its owner's hand.
Draw a card.

Flood

{U}{U}: Tap target creature without flying.

Tidebinder Mage

When Tidebinder Mage enters, tap target red or green creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control Tidebinder Mage.

Chillbringer

Flying
When Chillbringer enters, tap target creature an opponent controls. It doesn't untap during its controller's next untap step.

Aqueous Form

Enchant creature
Enchanted creature can't be blocked.
Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)