There are ten of these, two in each color, and they help the typal themes of the set by acting as a bridge between two of the creature types in their respective colors
But the reason behind it isn't what you think
This feels like WOTCs thesis project, trying to see if they can make activated abilities matter again
The odds seemed better, or at least more evenly distributed, with Prismatic Evolutions
It provides a traditional +1/+1 'lord' effect for your swashbuckling creatures, and all the merrier if you happen to have any Skeletons lying around
In the games that you win with this deck, you'll spend the early and middle stages of the game appearing as if you are accomplishing very little only to turn the corner in the late game and build a board that many other decks in the Upgraded Bracket (3) will struggle to interact with