Holmgang does prevent KB but it does it a helluva lot less effectively than Tempered Will. TW lasts longer, doesn't bind the user (so they can dodge all of the other stuff that the Titan throws alongside LSs), doesn't require a target to be nearby, and doesn't consume the user's uber-survivability CD in the process. As I've been saying since 2.1 release, Holmgang tries to do too much which makes it do none of those things well:
- Because it a binds the target, it can't have the duration that would make it useful for survival and physics immunity. Furthermore, it has to have limited range which means that the pull is basically worthless and, as a tank CD, it is more situational because something *has* to be right in your face.
- Because it's an uber-survivability ability, it can't have a CD that makes the bind/pull anything beyond a gimmick.
- Because it binds *you*, the survival and physics benefits are reduced because you're forced to eat whatever it is that's thrown at you for the next 7-8 seconds or so (if you get a red zone/plume thrown at the end, you're not going to be able to run out of it in time).
Holmgang really should be split into 3 separate abilities: a bind/pull (that binds you), an uber-survivability CD, and a physics immunity CD (you could split it into 2, but that would compromising the usefulness of one of the factors). A separate bind/pull would actually allow you to put it on a CD that makes those effects useful (45-60 secs) and only get yourself bound for the effect that actually requires you be bound for balance purposes; as separate uber-survivability tank CD would let you give it a duration that makes it have an appreciable effect (10 secs); a separate physics immunity CD would allow you to be immune to physics without getting stuck in one spot the entire time.
Adding 2 abilities to the class is probably a bit too much, so I'd be happy if they put the physics immunity on Unchained (keep the physics limited to a 10 sec duration; the 2 min CD is balanced by the Wrath requirement). Holmgang itself could stay as the bind/pull (since it's got the perfect animation for it in the first place). All that leaves is adding one extra ability (probably at level 50) for the uber-survivability (ACN already provides 18 instead of the standard 17 because it gets 2 abilities at 4 instead of only 1).