Agent of Treachery

When Agent of Treachery enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Command Tower

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

Wizard's Rockets

Wizard's Rockets enters tapped.
{X}, {T}, Sacrifice Wizard's Rockets: Add X mana in any combination of colors.
When Wizard's Rockets is put into a graveyard from the battlefield, draw a card.

Ancient Ziggurat

{T}: Add one mana of any color. Spend this mana only to cast a creature spell.

Command Beacon

{T}: Add {C}.
{T}, Sacrifice Command Beacon: Put your commander into your hand from the command zone.

Chromatic Sphere

{1}, {T}, Sacrifice Chromatic Sphere: Add one mana of any color. Draw a card.

Terrarion

Terrarion enters tapped.
{2}, {T}, Sacrifice Terrarion: Add two mana in any combination of colors.
When Terrarion is put into a graveyard from the battlefield, draw a card.

Barbed Sextant

{1}, {T}, Sacrifice Barbed Sextant: Add one mana of any color. Draw a card at the beginning of the next turn's upkeep.

Arcane Signet

Sen Triplets

At the beginning of your upkeep, choose target opponent. This turn, that player can't cast spells or activate abilities and plays with their hand revealed. You may play lands and cast spells from that player's hand this turn.

Chromatic Star

{1}, {T}, Sacrifice Chromatic Star: Add one mana of any color.
When Chromatic Star is put into a graveyard from the battlefield, draw a card.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Collector's Vault

{2}, {T}: Draw a card, then discard a card. Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

City of Brass

Whenever City of Brass becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Study Hall

{T}: Add {C}.
{1}, {T}: Add one mana of any color. When you spend this mana to cast your commander, scry X, where X is the number of times it's been cast from the command zone this game.