You may disable this orb after ring event in which Angremar the Black spawns. (Must disable orbs to spawn last named in zone.) Orb is black on a pedestal, mouse over and click. Should glow. 4 total orbs before magic shield falls and you can go for the named.
Crypt of T'haen:Vengeance ONLY (raid), disable all 4 orbs to make the magic wall disappear. Click the orb to make it glow and turn off. Names may need to spawn before orbs are clickable.
(raid zone), after you attack each mob in this room, a mob of dogs will spawn on you, all mobs will be heroic until you clear the room, then a mob of 3 epic dogs will spawn led by Smolder; kill Smolder and the Orb will be clickable, disable this last orb and you can proceed with the zone beyond the magic wall. It doesn't "look" like it's down, but it is, just walk thru.
lvl 54^^^ Heroic
Possible spawn during Funeral Pyre quest in regular CoT heroic zone, not Eternal Night instance, with at least 4 guardians of the slayer adds. So the cave may include Q'rin, then another named with adds, don't be hasty to click.