Sol Ring

Enduring Vitality

Vigilance
Creatures you control have "{T}: Add one mana of any color."
When Enduring Vitality dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Kestia, the Cultivator

Bestow {3}{G}{W}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Enchanted creature gets +4/+4.
Whenever an enchanted creature or enchantment creature you control attacks, draw a card.

Seaside Citadel

Seaside Citadel enters tapped.
{T}: Add {G}, {W}, or {U}.

Arcane Signet

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

Thought Vessel

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

Command Tower

Dryad of the Ilysian Grove

You may play an additional land on each of your turns.
Lands you control are every basic land type in addition to their other types.

Exotic Orchard

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

Sanctum Weaver

{T}: Add X mana of any one color, where X is the number of enchantments you control.