Orzhov Signet

Command Tower

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

Raffine's Tower

({T}: Add {W}, {U}, or {B}.)
Raffine's Tower enters the battlefield tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Dimir Signet

Tivit, Seller of Secrets

Flying, ward {3}
Council's dilemma — Whenever Tivit enters the battlefield or deals combat damage to a player, starting with you, each player votes for evidence or bribery. For each evidence vote, investigate. For each bribery vote, create a Treasure token.
While voting, you may vote an additional time. (The votes can be for different choices or for the same choice.)

Azorius Signet

Arcane Sanctum

Arcane Sanctum enters the battlefield tapped.
{T}: Add {W}, {U}, or {B}.

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.