a chained bazu  

I aggroed a few of these & after so many I got a Green Emote:

Zeigel One-eye shouts. "Quickly, release the Bazu! Release the beasts!"

After that you get an emote saying "Perhaps you can prevent the dragorn from reaching and then releasing all of the chained bazu."

Zeigel One-eye shouts. "Go! Get down there and release the chained bazu!"

At that point you get dragorns spawn, they run to the chained bazu & free them, whereupon they are unchained & change name to a rampaging bazu

Neither the chained bazu or the rampaging bazu can be damaged, after failing the bazu will eventually despawn.

If all of the chained bazu are freed you fail the event.

I don't know if there is any reward for a successful completion of this ring event, there were quite a few Dragorn and first time seeing this I missed the emotes and wasn't sure what was going on.