I've Heard Talk About Swarms, What Are They?

I've head people talking about it on the forums and was just wondering what it was

 

its when a shiton of mobs go into a city and kill everyone

 

Roughly what Yuno said.

As far as I can remember (I can only remember experiencing one swarm) :

It's when a ton of mobs attack a city. The old way it worked was that if you were on the world that was having a swarm you would see a warning in chat saying where the swarm was going to hit and how long until it hit. I believe there were 20min, 10min and 5min warnings. Generally lots of players would head to said city and find places to camp high up. Once the swarm starts, no-one can leave (or presumably enter) the city and mobs would start streaming in the city gates. The swarm would end once all the mobs had been defeated and everyone who hadn't died would get an xp bonus.

Couple of things I cant remember
-the level of the attacking mobs (though I think it would be related to the city level)
-the frequency of swarms
-if mobs spawned inside the city as well
-if you would respawn inside the city if you died

 

I've never tried it, but I think you can leave or enter a swarm area. I'm sure there have been people turning up at swarms after they start. Not sure about the 'everyone who hasn't died' either, because I haven't died in a swarm, but I'm sure people have died in swarms and then got the xp.
The mobs didn't have a level. It takes the same number of hits to kill a mob as anyone else. But because arrow storm and multihit can hit mobs more than once, lots of people used these (or you could even say abused, because they always killed the mobs you attacked).
Swarms happened daily, and could even happen two or even three times a day.
Mobs almost always spawned in the city. In fact, a whole group of mobs appeared in one place at the city gates (the 'main gate' if it had more than one way in). After that, they appeared everywhere inside the city.
You would respawn in the city.

 

Both the most fun and Least fun thing in wynn

 

I've never tried it but if it doesn't cause lag then I would definitely try it