Twiddle

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

Pemmin's Aura

Enchant creature
{U}: Untap enchanted creature.
{U}: Enchanted creature gains flying until end of turn.
{U}: Enchanted creature gains shroud until end of turn. (It can't be the target of spells or abilities.)
{1}: Enchanted creature gets +1/-1 or -1/+1 until end of turn.

Refocus

Cerulean Wisps

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

Umbral Mantle

Equipped creature has "{3}, {Q}: This creature gets +2/+2 until end of turn." ({Q} is the untap symbol.)
Equip {0}

Vitalize

Revelsong Horn

{1}, {T}, Tap an untapped creature you control: Target creature gets +1/+1 until end of turn.

Galvanic Alchemist

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

Springleaf Drum

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

Seeker of Skybreak

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

Archelos, Lagoon Mystic

As long as Archelos is tapped, other permanents enter tapped.
As long as Archelos is untapped, other permanents enter untapped.

Puppet Strings

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

Spectral Cloak

Enchant creature
Enchanted creature has shroud as long as it's untapped. (It can't be the target of spells or abilities.)

Jandor's Saddlebags

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.