Public Event

A Public Event is a global minigame in Destiny, where local players may participate in a game-determined objective in order to defend zones from enemies and earn loot. Public Events appear to be randomized and can occur at anytime anywhere in Destiny, where multiple fireteams may participate in combating waves of enemies before encountering a boss.

Fallen Assault
Fallen Assault was the first example of a Public Event which was featured at Destiny's live demo during the Sony press conference at E3 2013. The event included multiple waves of Fallen enemies before having a Fallen Devil Walker was dropped into the field.