It's Really Getting Out of Hand

Wait for Getting Out of Hand world quest to popup.
This world quest is located in Nazmir on the north-east coast, right behind the huge tuttle in Torga's Rest

20 seconds timers starts the moment you use Extra action button [spell=259742]
After you cast the extra action button you become [npc=131613] and have 3 spells

1. 
   
2. [spell=259747]
3. 
   
4. [spell=259769]
5. 
   
6. [spell=259794]
7. 
   

You need to kill 40 mobs in the area in 20 secons now.
Use only 2nd spell - it is the main damaging ability

It's Really Getting Out of Hand achievement demo video: https://www.youtube.com/watch?v=Jiz_kInYePc

Hint: You have time to prepare and agro more mobs in the area before you use [spell=259742]. (Probably can do without prepulling mobs, but it will make this achievement easier)
Mount and agro couple of packs in the middle of the area and move to one of the wooden platforms.
Get away from mobs (because you need to cast [spell=259742] for 3 secs), but don't loose agro and try to cast it as close to the wooden platforms as you can

These achievements that require world quests up are absolutely awful. This is the first time I've seen this WQ up since hitting 120 so failing it just ONCE could mean waiting *weeks* for it again.

Absolutely terrible. I shouldn't have to consider level alts just for an extra attempt or two every few weeks.

You can complete this by transforming into the hand (this starts the 20 second timer), then pressing the leave vehicle button to turn back into your normal self, then killing 40 mobs before the timer expires. If your class has good mobility and if you're max level, this is a great option.