Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When Breaching Hippocamp enters the battlefield, untap another target creature you control.

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Galvanic Alchemist

Soulbond (You may pair this creature with another unpaired creature when either enters the battlefield. They remain paired for as long as you control both of them.)
As long as Galvanic Alchemist is paired with another creature, each of those creatures has "{2}{U}: Untap this creature."

Trickster Mage

{U}, {T}, Discard a card: You may tap or untap target artifact, creature, or land.

Disciple of Deceit

Inspired — Whenever Disciple of Deceit becomes untapped, you may discard a nonland card. If you do, search your library for a card with the same mana value as that card, reveal it, put it into your hand, then shuffle.

Siege Zombie

Tap three untapped creatures you control: Each opponent loses 1 life.

Vault Skyward

Target creature gains flying until end of turn. Untap it.

Mothdust Changeling

Changeling (This card is every creature type.)
Tap an untapped creature you control: Mothdust Changeling gains flying until end of turn.

Shore Up

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.)

Survivors' Encampment

{T}: Add {C}.
{T}, Tap an untapped creature you control: Add one mana of any color.

Hidden Strings

You may tap or untap target permanent, then you may tap or untap another target permanent.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Corridor Monitor

When Corridor Monitor enters the battlefield, untap target artifact or creature you control.

Dramatic Reversal

Untap all nonland permanents you control.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Teardrop Kami

Sacrifice Teardrop Kami: You may tap or untap target creature.

Freed from the Real

Enchant creature
{U}: Tap enchanted creature.
{U}: Untap enchanted creature.

Stonybrook Angler

{1}{U}, {T}: You may tap or untap target creature.

Iceberg Titan

Whenever Iceberg Titan attacks, you may tap or untap target artifact or creature.

Inverted Iceberg

When Inverted Iceberg enters the battlefield, mill a card, then draw a card. (To mill a card, put the top card of your library into your graveyard.)
Craft with artifact {4}{U}{U} ({4}{U}{U}, Exile this artifact, Exile another artifact you control or an artifact card from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

Inverted Iceberg // Iceberg Titan

Vizier of Tumbling Sands

{T}: Untap another target permanent.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle Vizier of Tumbling Sands, untap target permanent.

Refocus

Twiddle

You may tap or untap target artifact, creature, or land.

Component Collector

If it's neither day nor night, it becomes day as Component Collector enters the battlefield.
Whenever day becomes night or night becomes day, you may tap or untap target nonland permanent.

Crypsis

Target creature you control gains protection from creatures your opponents control until end of turn. Untap it.

Clever Conjurer

Mage Hand — {T}: Untap target permanent not named Clever Conjurer. Activate only as a sorcery.

Coral Trickster

Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Coral Trickster is turned face up, you may tap or untap target permanent.

Dream's Grip

Choose one —
• Tap target permanent.
• Untap target permanent.
Entwine {1} (Choose both if you pay the entwine cost.)

Holdout Settlement

{T}: Add {C}. ({C} represents colorless mana.)
{T}, Tap an untapped creature you control: Add one mana of any color.

Toils of Night and Day

You may tap or untap target permanent, then you may tap or untap another target permanent.

Galvanic Key

Cerulean Wisps

Target creature becomes blue until end of turn. Untap that creature.
Draw a card.

Twitch

You may tap or untap target artifact, creature, or land.
Draw a card.

Narcolepsy

Enchant creature
At the beginning of each upkeep, if enchanted creature is untapped, tap it.

Psychic Puppetry

You may tap or untap target permanent.
Splice onto Arcane {U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)