The Overo Skin is an exotic skin only obtainable through nesting. It is attained by breeding two dragons with a Black Melanistic Kickstarter skin and a White Leucistic Kickstarter skin. The chances of Overo being produced from a Melanistic/Leucistic pair is currently unknown; however, within the closed beta, this skin mutation had a 40% chance of occurring during breeding.
There is currently no information on how this skin will look on non-implemented dragons.
Below are the dragons with the Overo skin and how they look in the game:
As the overo skin is an exotic skin, it cannot be combined any further.