Could be an expansion release, guild drama, random encounter, etc.
Mine would be when I was a newer player doing a Twilight Arbor dungeon run with veterans and I enabled "Plant Mode".
I was the classic Longbow ranger with Stalker who had no idea wtf was going on. We got to the wardens on Leurent's path (up) and it was not going well, I kept going down. The others in my party kept reviving me but in doing so were downed and then killed. The champ probably had about 2% health left when I was the last one standing and I am sweating IRL - mainly nervous that I'm going to get chewed out by the other party members if I can't finish the fight.
One of the party members types "Just spam all your buttons!" so I start clicking anything and everything (yes, was a mouse ability clicker back then... how times have changed).
I don't think I had ever used my elite at that point, mainly because I didn't understand it. I just knew it said something about plants. Ended up clicking Take Root and was instantly felt dread. My character was locked down and I couldn't move as I became enshrouded with plant matter.
As if to further cement the absolute embarrassment that was washing over me, the same party member goes "Plant mode?!".
I seriously considered alt+F4'ing to hide from my shame - only to realize that I wasn't taking any damage anymore... And that there were seed turrets spawning all over as if to save me. They started attacking the Champ and it ticked down another % or so - it was so close to dying!
Then my protective plant shroud disappeared and I was running again, desperately trying to live. However, I was still so low from before I had initially cast the elite that I was quickly downed. Instantly I spammed "Lick Wounds" (As many downs in the open world had taught me).
As I inched closer to death another party members says "OMG It's so close". Fractions of a second before I was about to die my pet starts reviving me - and it happens. One of the slow arching shots of the plant mortar near me lands the final blow on the champion and I revive - I was absolutely stunned.
My party was absolutely ecstatic and kept typing things like "Plant mode ftw" and "Salad mvp". In that moment I felt like I was a seasoned GW2 player just like the rest.
Definitely died to the root attack from the nightmare tree just moments after that though.
Neat!