Citadel Siege

As Citadel Siege enters, choose Khans or Dragons.
• Khans — At the beginning of combat on your turn, put two +1/+1 counters on target creature you control.
• Dragons — At the beginning of combat on each opponent's turn, tap target creature that player controls.

Timin, Youthful Geist

Partner with Rhoda, Geist Avenger (When this creature enters, target player may put Rhoda into their hand from their library, then shuffle.)
Flying
At the beginning of each combat, tap up to one target creature.

Scepter of Dominance

Gideon's Avenger

Whenever a creature an opponent controls becomes tapped, put a +1/+1 counter on Gideon's Avenger.

Nomad Decoy

{W}, {T}: Tap target creature.
Threshold — {W}{W}, {T}: Tap two target creatures. Activate only if seven or more cards are in your graveyard.

Avacynian Priest

Kelpie Guide

{T}: Untap another target permanent you control.
{T}: Tap target permanent. Activate only if you control eight or more lands.

Icebind Pillar

{S}, {T}: Tap target artifact or creature. ({S} can be paid with one mana from a snow source.)

Telekinetic Sliver

All Slivers have "{T}: Tap target permanent."

Rhoda, Geist Avenger

Partner with Timin, Youthful Geist (When this creature enters, target player may put Timin into their hand from their library, then shuffle.)
Vigilance
Whenever a creature an opponent controls becomes tapped, if it isn't being declared as an attacker, put a +1/+1 counter on Rhoda, Geist Avenger.

Sand Squid

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
You may choose not to untap Sand Squid during your untap step.
{T}: Tap target creature. That creature doesn't untap during its controller's untap step for as long as Sand Squid remains tapped.

Gideon's Lawkeeper

Cryptic Command

Choose two —
• Counter target spell.
• Return target permanent to its owner's hand.
• Tap all creatures your opponents control.
• Draw a card.

Betrayal

Enchant creature an opponent controls
Whenever enchanted creature becomes tapped, you draw a card.

Benalish Trapper

Master Decoy

Squall Drifter

Sentinel of the Eternal Watch

Vigilance (Attacking doesn't cause this creature to tap.)
At the beginning of combat on each opponent's turn, tap target creature that player controls.

Goldmeadow Harrier

Blinding Drone

Devoid (This card has no color.)
{C}, {T}: Tap target creature. ({C} represents colorless mana.)

Sigardian Priest

Proud Mentor

Partner with Impetuous Protege (When this creature enters, target player may put Impetuous Protege into their hand from their library, then shuffle.)
{W}, {T}: Tap target creature.

Verity Circle

Whenever a creature an opponent controls becomes tapped, if it isn't being declared as an attacker, you may draw a card.
{4}{U}: Tap target creature without flying.

Blinding Mage

Ballynock Trapper

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

Minister of Impediments

({W/U} can be paid with either {W} or {U}.)
{T}: Tap target creature.

Whipcorder

{W}, {T}: Tap target creature.
Morph {W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Octopus Umbra

Enchant creature
Enchanted creature has base power and toughness 8/8 and has "Whenever this creature attacks, you may tap target creature with power 8 or less."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)