The five Invasion Dragon Legends might all be three-colored gold cards, but their abilities are all tied closely to specific colors.
Each dragon is made of three colors of mana that are next to each other on the color wheel. Rith, the Awakener, for example, costs 
. The Dragon's activated abilities are all linked to the middle color in the cost. Rith is essentially the "green dragon," as his ability to put Saprolings into play is green.
Crosis, the Purger is the black dragon, and forces discard. Treva, the Renewer is the white dragon that gains you life. Dromar, the Banisher is the blue bouncy dragon. And Darigaaz, the Igniter is red, and burns people up.