Board Thread:Dragon City Gameplay Questions & Answers/@comment-41.129.61.114-20130619200125/@comment-9946604-20130620060542

Note on rare hybrids:

Rare hybrids have oposite elements (Dark and Sea in the case of Pirate).

You can't breed them directly. At least ONE parent needs to be a hybrid. Both can be hybrids, but this is not necessesary and actually just adds one more element to the mix.

Some combinations are especially annoying as they can result in basic elemental dragons or other random dragons you don't need.

EX: Watefall Dragon (Terra Sea) and Hedgehog (Terra Dark). This can yield: Pirate, Petroleum (also a dark water rare), Waterfall, Mud, Hedgehog, Venom and (sadly) basic Terra.

By contrast,  Waterfall plus Dark will be either Hedgehog, Venom, Pirate, or Petroleum. The advantages are that it's easier to figure out what you have from breed time and all of those dragons have good income (except petroleum who is an excellent fighter) and are probably worth keeping.