All permanents are artifacts in addition to their other types. All cards that aren't on the battlefield, spells, and permanents are colorless. Players may spend mana as though it were mana of any color.

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.)

As Three Tree City enters, choose a creature type. {T}: Add {C}. {2}, {T}: Choose a color. Add an amount of mana of that color equal to the number of creatures you control of the chosen type.