I recommend ignoring the stranglers on the Cancroid fight. Why? Because if they are spawning, then your group DPS is already on the low side. And their spawn increases with time. So if the fight is already dragging out because of low DPS, then expending damage on the stranglers instead of the main targets will only serve to prolong the fight even more. And it doesn't take much to get to the point where stranglers are literally spawning faster than they can be killed.

The threat posed by the stranglers come not from theirs projectile hits (which is called Spit), but from the DoT resulting from those projectiles (which, confusingly, is also named Spit). This DoT is stackable and does damage on the order of about 1K/s per stack. If you just have a couple of stacks of the DoT, the damage is inconsequential and you can't even feel it. If you have 10 stacks of the DoT, you're a dead man walking. The key to dealing with the stranglers is to end the fight as quickly as possible (i.e., don't waste damage on the stranglers) and to use Efficient Purge to eliminate the DoT (which also resets the stacks to zero).

There's more about boss 3, boss 4, and boss 5 HM in various posts on the forum.

Great guide, I’ll use this when I get around to trying the new dungeon. Are there differences in hard mode and is it a scroll or conditional trigger?