When he flashes and tries to blind you, I would suggest you to hide behind a piller rather than teleporting away. As my "research" shows, teleporting away takes extra clicks and, sadly, teleporting just before the blast will protect you from the damage, but your stats will still go down.

The beasitary says:

Its most dangerous attack is a blast of energy, which it charges up, getting a yellow glow around it for a second. You must hide behind a pillar or use a gatestone teleport to avoid this attack. If you get hit by it, you will take a large amount of damage, and your combat stats will be significantly decreased. It does not have a damage type, so prayers are useless against it.

 

So wheres the correction?

It tells you both options (tele or hide) and bolds hide to emphasis it is the easier and better choice.

I've played with a few people who actually prefer teleporting out each time. There won't be any summoned familiars interfering with clicking the teleport button, but in a hectic 5-man team they sometimes do mess up those who would left-click to walk behind the pillar. Clearly trying to interact with a familiar is more important than avoiding one of the most lethal attacks in the game. Thanks for that one, Jagex :P

 

So while hiding behind a pillar remains the preferred way of handling things (which is as Sy pointed out, stressed by the bold text), the teleportation method may provide a solution to the few people who struggle. I hope that sounds reasonable?