It should be noted that the Killer’s Insight feat (please correct me if this is not the feat to which you were referring) allows you to only add an additional, second shroud to your target once per encounter. The assassin can use the feat to get two shroud charges at once for +2d6 damage, but it can only be done once per encounter and provides no further benefit once the charges have been used. If the assassin was to build only one shroud charge per round and spend it immediately, it would be a +1d6 bonus to damage, which is comparable to Ranger, Warlock, and to a lesser extent Barbarian. Only in one round per encounter can it reach the Rogue’s +2d6 output.

I agree with you that Assassin’s Shroud is most assuredly the primary striker damage source for the class, with Night Stalker as a build choice for a little bonus. However, it would appear to be balanced against the other strikers without threatening the Rogue due to the removal of shroud charges after use.

The shroud lets, as a base the Assassin add +1d6 to damage to one damage roll each round. This is the same as the Ranger or Warlock’s “striker bonus” (in part). He can also take a feat that makes it +2d6 to one damage roll each round. This is the same as Sneak Attack, except you don’t need CA. And it even does damage on a miss (which I hadn’t noticed before!), which puts it a bit above Quarry (to make up for the lack of multi-attacks), and helps to offset the Rogue’s accuracy (I guess, still seems better than Sneak Attack to me). So yes, I’m sure that is the striker bonus. I don’t see how it’s weak–it can either be equivalent to other striker bonus damage sources, or you can stack it up to give a single enemy a big hit (effectively, not applying your Quarry to a minion one round in order to add it twice to the solo the next).

If you look at the sheet of Feats, you’ll see that “Night Stalker” is a guild training ability (sounds like a guild feat, or may be a new set feat he took. It may be an assassin class feature (their build choice), in which case they have two sources of extra “striker” damage (basically an extra tagger if they can get special circumstances). That ability by itself is pretty weak, as it’s situational and harder to get/control than CA. [though an assassin and an Avenger seem like they could work nicely together...] The shroud is much better than the Night Stalker ability, and would be an assassin’s primary source of extra damage.

Also, with Killer Instinct you can be doing Sneak Attack each round at will, without needing Combat Advantage. And can use a big sword to do it. Rogue is sad?

Good catch about the magic items! Though they can use their Ki powers instead of a weapon, so at least they’re covered there