Brontodon King

This page was last updated during patch v1.3.1869. The current patch is .
(In discussions, the acronym 'BK' is frequently used to reference this event)
The Brontodon King is a large Open World boss battle. It is very popular and typically announced and discussed in the in-game chat.
The encounter can spawn in Coral Forest or Sertao, and in terms of scale, is approximately the same size as a Melding Tornado, taking upwards of 10-15 players working together to fell this massive beast. Should you succeed, you’ll have earned yourself a shot at receiving one of several new brand-new rewards which are unique to this encounter.
In Coral Forest, BK always spawns around the Stonewall area, in the southern central portion of the map. In Sertao, the location will vary. Many times BK will coincide with other events, such as a Bandit event or Melding Tornado.
Both zones will spawn BK approximately once per hour, with the timer starting from the end of the previous event. As such, you can schedule your gameplay so that you always participate in this event. An addon is available in the official forum which displays the time left until the event spawns.
Depending on how many players show up to the event, and the weaponry and skill of the players, the BK event can end very quickly (within 2 minutes), or can last upwards of 15 minutes.
XP rewards for this event will typically range from 40K to 70K.
Bugs:
It is widely known that the event does not always reward xp, and there is debate over exactly what causes this bug, and also debate over what qualifies as sufficient participation, but generally, only a little participation is needed to receive the large reward. A quick way to assure participation is to kill some of the additional Brontodons that spawn during the event rather than focusing all your attention on the King. 
Tips:
BK has the ability to stun you and your battleframe's energy system if you are in range, as well as inflict massive damage with a physical swing of its' tusks. When learning the event, it is best to stay out of range of it's stun ability. As you play the event, you will see a red ring appear on the ground every 30 seconds or so, indicating the danger zone.
If you are inside the ring, you will be knocked to the ground and rendered vulnerable to additional BK attacks. Additionally, once you are back on your feet, your jump jets will remain offline for 15 seconds or so.
BK also has the ability to 'lock on' to you if you leave the ringed area at the time it begins its' attack sequence.