Galvanic Key

Fatestitcher

{T}: You may tap or untap another target permanent.
Unearth {U} ({U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Captain of the Mists

Whenever another Human you control enters, untap Captain of the Mists.
{1}{U}, {T}: You may tap or untap target permanent.

Tradewind Rider

Flying
{T}, Tap two untapped creatures you control: Return target permanent to its owner's hand.

Estrid, the Masked

+2: Untap each enchanted permanent you control.
−1: Create a white Aura enchantment token named Mask attached to another target permanent. The token has enchant permanent and umbra armor.
−7: Mill seven cards. Return all non-Aura enchantment cards from your graveyard to the battlefield, then do the same for Aura cards.
Estrid, the Masked can be your commander.

Cerulean Wisps

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

Chain Stasis

You may tap or untap target creature. Then that creature's controller may pay {2}{U}. If the player does, they may copy this spell and may choose a new target for that copy.

Barrenton Medic

{T}: Prevent the next 1 damage that would be dealt to any target this turn.
Put a -1/-1 counter on Barrenton Medic: Untap Barrenton Medic.

Garruk Wildspeaker

+1: Untap two target lands.
−1: Create a 3/3 green Beast creature token.
−4: Creatures you control get +3/+3 and gain trample until end of turn.

Candelabra of Tawnos

Blasting Station

{T}, Sacrifice a creature: Blasting Station deals 1 damage to any target.
Whenever a creature enters, you may untap Blasting Station.

Galecaster Colossus

Tap an untapped Wizard you control: Return target nonland permanent you don't control to its owner's hand.

Filigree Sages

Clock of Omens

Tap two untapped artifacts you control: Untap target artifact.

Beacon Hawk

Flying
Whenever Beacon Hawk deals combat damage to a player, you may untap target creature.
{W}: Beacon Hawk gets +0/+1 until end of turn.

Chakram Slinger

Partner with Chakram Retriever (When this creature enters, target player may put Chakram Retriever into their hand from their library, then shuffle.)
{R}, {T}: Chakram Slinger deals 2 damage to target player or planeswalker.

Glare of Subdual

Tap an untapped creature you control: Tap target artifact or creature.

Elder Druid

{3}{G}, {T}: You may tap or untap target artifact, creature, or land.

Arbor Elf

Aboshan, Cephalid Emperor

Tap an untapped Octopus you control: Tap target permanent.
{U}{U}{U}: Tap all creatures without flying.

Dross Scorpion

Whenever Dross Scorpion or another artifact creature dies, you may untap target artifact.

Chakram Retriever

Partner with Chakram Slinger (When this creature enters, target player may put Chakram Slinger into their hand from their library, then shuffle.)
Whenever you cast a spell during your turn, untap target creature.

Earthcraft

Tap an untapped creature you control: Untap target basic land.

Ghostly Touch

Enchant creature
Enchanted creature has "Whenever this creature attacks, you may tap or untap target permanent."

Aphetto Grifter

Tap two untapped Wizards you control: Tap target permanent.

Companion of the Trials

Flying
{1}{W}: Untap target creature. Activate only if you control a Gideon planeswalker.

Ethersworn Adjudicator

Flying
{1}{W}{B}, {T}: Destroy target creature or enchantment.
{2}{U}: Untap Ethersworn Adjudicator.

Deserted Temple

{T}: Add {C}.
{1}, {T}: Untap target land.

Gilder Bairn

{2}{G/U}, {Q}: Double the number of each kind of counter on target permanent. ({Q} is the untap symbol.)

Fyndhorn Brownie

Aphetto Alchemist

{T}: Untap target artifact or creature.
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.)

Crackleburr

{U/R}{U/R}, {T}, Tap two untapped red creatures you control: Crackleburr deals 3 damage to any target.
{U/R}{U/R}, {Q}, Untap two tapped blue creatures you control: Return target creature to its owner's hand. ({Q} is the untap symbol.)

Argothian Elder

Derevi, Empyrial Tactician

Flying
When Derevi, Empyrial Tactician enters and whenever a creature you control deals combat damage to a player, you may tap or untap target permanent.
{1}{G}{W}{U}: Put Derevi onto the battlefield from the command zone.

Grand Architect

Other blue creatures you control get +1/+1.
{U}: Target artifact creature becomes blue until end of turn.
Tap an untapped blue creature you control: Add {C}{C}. Spend this mana only to cast artifact spells or activate abilities of artifacts.

Benthicore

When Benthicore enters, create two 1/1 blue Merfolk Wizard creature tokens.
Tap two untapped Merfolk you control: Untap Benthicore. It gains shroud until end of turn. (It can't be the target of spells or abilities.)

Ballynock Trapper

{T}: Tap target creature.
Whenever you cast a white spell, you may untap Ballynock Trapper.