Tanks/healers without the gear to power through this easily should burn cooldowns until the adds are dead, at which point Bjarngrim will lose Electrical Charge and becomes a glorified tank-and-spank (as long as your melee stay out of the whirlwind. If they don't, it becomes a long glorified tank-and-spank).
This was another achievement my group got entirely by accident. Until I actually sat down to look up information for this article, I confess my usual advice to groups was, "I'll pull him back and you burn him down...I think."
It turns out that's still decent advice, because all you need to do is kill Volkhan before he shatters 4 of his summoned golems. While this is a DPS check, it's not a particularly strong one, and most groups can kill him well before that point. However, if your damage isn't that great, you're best off killing adds as necessary. This should be an easier task for ranged DPS, as the golems get slower and slower as their health drops. However, because Volkhan will continually summon these golems during the fight, you're still better off just burning him down.
Because this (and the Loken achievement, next) is one of the easiest DPS checks for the meta Glory of the Hero, Halls of Lightning is a good trial heroic to evaluate the damage capability of your group. If you have trouble with HoL, you may want to postpone tougher DPS-dependent achievements like Less-rabi and Volazj's Quick Demise.
Easy, easy, easy. And yes, I said that about Loken.
The deal with Loken is that, despite being the scourge of early Wrath heroic groups, he doesn't actually have a lot of health. In order to get him down within 2 minutes, your three DPS need to manage a little less than 1,500 DPS each. Given that your tank will also be doing some damage, the true DPS requirement is even less, and probably closer to about 1,100-1,200. If your group can't manage this, there's a lot in Glory of the Hero that's going to be difficult or outright impossible.
Groups with a strong AoE healer will sometimes elect to stay in for Lightning Nova and simply heal through it to preserve uninterrupted DPS time, but to be perfectly honest I think that's an unnecessary stress on the healer (although I'll grant that, as someone who's often Resto, I also have a reflexive dislike for dumping all responsibility on the healer just because the DPS can't be arsed to budge). Now, if your healer doesn't object to it and each group member has at least 16K health, don't let me stop you, but generally my groups move out for the Nova.
Keep Loken tanked on the strip of light running between his throne and the large globe in the center of the hall. When he emotes that he's casting the Nova, use your mouse to flip your character around quickly and run in the opposite direction on the strip until the Nova hits. Immediately flip back around to meet Loken again. Lather, rinse, repeat. Eventually you'll be unable to move any further as you'll hit the globe; simply rotate Loken until your back is to his throne. At no time do you ever need to move from the strip.The only real secrets are:
Keep your back to the direction in which you need to run: If you have to run through or around Loken, you'll get hit by the Nova.
Do not keyboard turn: This will kill you. If you're uncomfortable using the mouse to turn, simply strafe out of the Nova along the strip.
Keep the group together: His AoE damage pulse is much worse if people spread out. While this is somewhat more difficult on Hunters, keep the group as clumped as possible.
If your group lacks the coordination to do this, things like Oculus are going to be an absolute nightmare, which is one of the reasons that I really don't suggest the "lol heal through it" strategy; it gets people accustomed to shoving responsibility to one or two group members, and that's no good. If your group kills Loken quickly and cleanly with no practice or only a bit, then uninspiring DPS or notso-hotso gear can be fixed. If your group is all blues or epics but can't kill Loken without people dying or getting hit by the Nova, you may want to reevaluatewhether they're ready for the tougher heroics.