Ever wondered how people get SOOOOO MUCH damage against World Boss while you get scraps? Even though you have similar attack?
The answer may very well be double attacking the boss
What is Double Attack?
To put it simply, it is allowing your character to auto attack the boss followed by a skill.
How do I double attack?
That's easy!
To land a double attack you must time the activation of your skills properly. Easiest way is to watch for your character to begin an auto attack then immediately activate a skill.
Now keep in mind lag and not activating the skill in time will mean you don't auto and use skill in one attack (Double attack) so it does take a little bit of experience and practise to get the hang of it.
Another thing to be mindful about is what skill you are using, for example Thunderer takes longer to cast than Rain of Fire, so being able to use Thunderer in a double attack is unheard of, some claim they've done it, I call bullshit.
Below I have provided a video of a mage doing some double attacks with perfect precision.
Just to give you of an idea of how it looks.
Kudos to GingerTheHutt for providing the video.