Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Ornamental Courage

Untap target creature. It gets +1/+3 until end of turn.

Xavier Sal, Infested Captain

{T}, Remove a counter from another permanent you control: Populate. Activate only as a sorcery. (Create a token that's a copy of a creature token you control.)
{T}, Sacrifice another creature: Proliferate. Activate only as a sorcery. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Scryb Ranger

Flash
Flying, protection from blue
Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Sol Ring

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Retreat to Coralhelm

Landfall — Whenever a land enters the battlefield under your control, choose one —
• You may tap or untap target creature.
• Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Counterspell

Magewright's Stone

{1}, {T}: Untap target creature that has an activated ability with {T} in its cost.

Niblis of the Breath

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

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Teardrop Kami

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

Stonybrook Angler

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

Refocus

Thousand-Year Elixir

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

Negate

Seeker of Skybreak

Vorinclex, Voice of Hunger

Trample
Whenever you tap a land for mana, add one mana of any type that land produced.
Whenever an opponent taps a land for mana, that land doesn't untap during its controller's next untap step.

Staff of Domination

{1}: Untap Staff of Domination.
{2}, {T}: You gain 1 life.
{3}, {T}: Untap target creature.
{4}, {T}: Tap target creature.
{5}, {T}: Draw a card.

Puppet Strings

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

Jandor's Saddlebags

Puppeteer

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

Chakram Retriever

Partner with Chakram Slinger (When this creature enters the battlefield, 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.