The act of calling a dragon, with many purposes.
The dragon call is a deadly art passed down from generation to generation of Asians. This act takes many years to master, and is often the cause of death due to inexperience of use.
Though, there are few masters of the legendary dragon call living to this day.
Often categorized within the ninja arts, it is possibly the most deadly, efficient, and bad-ass ninjutsu summoning technique to date.
Usually done by the Asian race in order to seek revenge upon others who have undermined them.
This is done by clasping the hands together to form a "hollow sphere" and is then blown into through the thumbs to create a sort of whistling noise.
This can be done in different tones and notes to achieve various tunes, which determine the type of dragon summoned.
In conclusion, don't mess with asians.
I've done the dragon call before and I'm Asian. Trust me, it works.
Famous Asians have supposedly mastered this kickass art, most notably Bruce Lee, Jet Li, and Jackie Chan.