I started back up a month ago and have been doing all the chest events I can.
I've seen multiple notifications from guildies and folks in Lion's Arch when the various events come up.
I have never seen Lion's Arch or my guild for that matter give a notification for Megadestroyer. As a result, I have never done the encounter.
Why is this enemy avoided? Is there some fail condition linked to an NPC made out of glass?