Arcane Signet

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

Sol Ring

Castle Vantress enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Castle Embereth enters tapped unless you control a Mountain.
{T}: Add {R}.
{1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.

{T}: Add {C}.
{T}: Add {U} or {R}. Talisman of Creativity deals 1 damage to you.

You have no maximum hand size.
{T}: Add {C}.