Goblin King/Dark King?

This would be a hero, that can be gained from 3 starring all single player villages. (Maybe even add him as a defense on the last level...). I suggest him to be really small and at the home base, come out of a cave (lined with gold, elixier and dark elixier) instead of a podium like the king and queen. When raiding, this goblin hero would be activated by tapping on a resource building (storages, collectors etc). He would then charge at this, being invincible and able to jump walls like hog riders. Upon reaching the goal, he would collect all available resources (but not dealing damage) and then charge back out, however, he would then become vulnerable to defenses targeting him. He should probably have low health (2-3 hits from defenses) so that players have to figure out how to shield him from the enemy defenses. If the hero manages to escape the enemy village with the resources, these then become yours and are added to your storages.

On defense, the goblin hero might target enemy units that are attacking resource buildings or guard the loot from your town hall..

Not too sure about any abilities for this goblin. Appearance changes from normal gobins may include a hood?

I like this idea, but I don't think you should make the gblin king be able to jump over walls, because that's the hog rider's specialty.