Got 3 good dps in PUG and failed after 4 hours attempt.
Those spiders are the real boss,HM meaning they cant be CCed
They absolutely can be CC'ed. At the moment they spawn, dodge roll and cast your CC ability at the same time. The shalks will be snared at the point they spawn.
You are trying to use Grave Grasp, which doesn't work the way you think it does.
As Necro, you will have to put Agony Totem down before you dodge the attack.
In the end, it was things like this and lack of a heal not dependent on other stuff, that made me move away from Necro for tanking the hardest DLC HMs.
There is the issue of cc immunity added to game mobs and this boss not being addressed to balance it, but I am sorry bud, after watching the video, this one is entirely on you.
1. grave grasp stuns and immobolizes only in the ranged areas, the first 6m has small snare added to it.
2. using caltrops/agony totem/time stop would have been more useful.
3. Drop block and gtfo, you managed to get 12 stacks from the beetle. That's waaaaay too much pain. there is a reason I refuse to tank the hm on anything other than sorc. Mobility is king there.