Transguild Courier appears in a multicolored card frame, but it's still an artifact.

This card is white, blue, black, red, and green in all zones. It is multicolored.

Although originally printed with a characteristic-defining ability that defined its color, this card now has a color indicator. This color indicator can't be affected by text-changing effects (such as the one created by Crystal Spray), although color-changing effects can still overwrite it.