This is the result of channeling my frustration with Guild Wars 1 (why yes, I do still play a 15-year-old MMORPG, and you can too, the official servers are still up) into art.

Lemme tell ya a little story. There are these monsters in the Nightfall expansion called Roaring Ethers. Design-wise, they're among my favorite enemies in the game. Hence my drawing one. But gameplay-wise, they are my LEAST favorite mob type to fight in the entire game.
You see one of them in a group of mobs, no worries. I can DPS 'em down like everything else. You see two? Bit frustrating, but still manageable. Three or more, we start getting into bash-your-head-against-a-brick-wall territory. What you have to understand about Roaring Ethers is that they can revive one another. Ever play Twilight Princess? Remember the shield-face Twilight monster things you have to kill all at once as Wolf Link or they screech and their fallen buddies get back up? Imagine that, but one hundred times worse.
First off, they're fast. They use the basic player skill Resurrection Signet, which takes a mere three seconds to cast, to get their friends back into the fight. Players are limited in using this skill - you can only use it once, and it recharges if you manage to kill a boss mob. Roaring Ethers have no such limitations. They can cast that signet as often as they like. Did I mention that it also happens to revive those evil bastards at FULL HEALTH? It's easy to get caught in a loop of killing one Roaring Ether only for its buddy to fully resurrect it, and as soon as you kill that second one, the first one is returning the favor.
Second, they're Mesmers, and they're loaded up on spells that will zap your energy, making it really difficult to unload skills on them to DPS them down before they can start healing each other.
Third... Guild Wars 1 is really hard, okay? I'm far from the best player, but I'm no slouch! I had to work really hard for about a year to grind out 30 Hall of Monuments points to get rewards in Guild Wars 2. I've beaten all the campaigns and done a bunch of extra stuff in service of the aforementioned HoM points. I kind of like Vanquishing areas, when I have the time and focus to sit down and commit effort to it.
But these fuckers. THESE UNHOLY ABOMINATIONS. Were long the bane of my existence. It took me four or five tries, spread out over months, to successfully Vanquish the Hidden City of Ahdashim, and it's all because of THIS motherfucker, Yammirvu, Ether Guardian, and his entourage of Roaring Ether lackeys. Of course they would put the most annoying boss waaay deep into the bowels of the place so you have to put in time fighting through hordes of Djinn just for the pleasure to facegrind this pseudo-immortal bastard. Hope you don't die and get a -15% to attributes Death Penalty on your way there! And good luck finishing the rest of the zone once you rack up -60% fighting him! You better be able to afford a conset to bring. Heck, you'll need two.

So this is my rant, and my tribute. The best to look at, and the worst to fight. Oldskool ANet made something truly hardcore, and truly memorable. Bastards.