What's the purpose of the golden horn that has a play function and awards you gold coins?

This has changed a little recently, it used to summon a dragon, but the purpose is the same. At varying intervals of time you can blow the horn and summon enemies to then battle and earn gold. the amount you get can also vary and there is the option to watch an advert to double the amount. The time out on it will be a little random but will generally increase with each time you use it during each day.