Niblis of the Breath

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

Civic Gardener

Whenever Civic Gardener attacks, untap target creature or land.

Initiate's Companion

Whenever Initiate's Companion deals combat damage to a player, untap target creature or land.

Corridor Monitor

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

Burst of Energy

Merfolk Skyscout

Flying
Whenever Merfolk Skyscout attacks or blocks, untap target permanent.

Puppeteer

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

Stinging Lionfish

Whenever you cast your first spell during each opponent's turn, you may tap or untap target nonland permanent.

Militia Rallier

Militia Rallier can't attack alone.
Whenever Militia Rallier attacks, untap target creature.

Thistledown Players

Whenever Thistledown Players attacks, untap target nonland permanent.

Garth One-Eye

{T}: Choose a card name that hasn't been chosen from among Disenchant, Braingeyser, Terror, Shivan Dragon, Regrowth, and Black Lotus. Create a copy of the card with the chosen name. You may cast the copy. (You still pay its costs.)

Elmar, Ulvenwald Informant

Haste
Whenever you cast your second spell each turn, untap target creature, then investigate. (Create a colorless Clue artifact token with "{2}, Sacrifice this artifact: Draw a card.")
Friends forever (You can have two commanders if both have friends forever.)

Tolarian Kraken

Whenever you draw a card, you may pay {1}. When you do, you may tap or untap target creature.