The hardest part during that fight was when he teleported and my tank was being charmed. Took me a few attempts to figure out a good positioning and strategy.

Group Setup:
Pally Tank
3x Ele DPS
Shammy Healer

Positioning:
Leave Healer at the top of the stairs, on the rubble elevated corner lip , closest to Arugal.
Keep DPS following tank.
Run up the ramp, NOT the stairs, as this will give you time to get all your followers up onto the platform before engaging.
Mash your spreadout key just before you get to him.

The Kill:
This may seem weird but, don't keep aggro on your tank. Reason being is you don't want to be charmed and run around.
Have your healer keep your DPS up as they will be taking the void bolts.
When he teleports, tap your follow macro, reposition as needed. Usually just requires a quick 90* turn.

He goes down pretty quick. My first clear in SFK was lvl 20 after getting my water totems. Ran it untill 24 and moved onto RFK.