Puppet Strings

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

Magewright's Stone

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

Ashnod's Altar

Jandor's Saddlebags

False Floor

False Floor enters tapped.
Creatures enter tapped.
{2}, {T}, Exile False Floor: Exile all untapped creatures. Activate only as a sorcery.

Fain, the Broker

{T}, Sacrifice a creature: Put two +1/+1 counters on target creature.
{T}, Remove a counter from a creature you control: Create a Treasure token.
{T}, Sacrifice an artifact: Create a 2/1 white and black Inkling creature token with flying.
{3}{B}: Untap Fain, the Broker.

Onyx Talisman

Whenever a player casts a black spell, you may pay {3}. If you do, untap target permanent.

Patriar's Seal

{T}: Add one mana of any color.
{1}, {T}: Untap target legendary creature you control.

Pitiless Plunderer

Whenever another creature you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.