So, I haven't seen this mentioned in any of the ToB threads I've been reading, where people do a ton of confusing multiclassing/etc. to get 9th level maneuvers in all disciplines.
I think I found an easier way to be a master of nine(if nobody noticed this yet). You see, unlike the other ToB prestige classes, in the Maneuvers entry, it says:
Maneuvers: At each odd-numbered level, you gain two new maneuvers known from any of the nine disciplines. At each even-numbered level, you gain one knew maneuver from any of the nine disciplines...
...At each level, you gain an additional maneuver readied per day.
Which means that Master of Nine is unique in that it's the only PrC which Legacy Champion can increase the maneuvers known/readied. (The only downside is that the stances known call out level 2 and 4 specifically, and therefore can't be progressed further RAW)
This is the simplest of simple builds, but Unarmed Swordsage 7/Master of Nine 5/Legacy Champion 8 (In that order)
IL 19
34 maneuvers known
15(!) maneuvers readied
5 stances (weakness)
22 rounds of dual stance per day
You have a bad-ass legacy weapon
I'm not that adept at figuring out how the hell multiple ToB base classes work with PrCs, but I'm sure someone could make something much scarier than what I have done here.
The main advantages here compared to the other True Master of Nine builds is that you have 15 maneuvers readied from a single initiator class, and that class has all nine disciplines throroughly covered, allowing great versitility. Also, using the Adaptive Stance feat you have as a pre-requisite works really well with White Raven Tactics and/or Moment of Alacrity, allowing you to refresh and swap out maneuvers to be the ultimate swiss army knife of melee in mid-high levels.
The weakness is a lack of high-level stances, which can be mitigated with some creative multiclassing dips at high levels, and generous helpings of the Martial Stance feat.
(As an aside, most of the 9th level maneuvers are boring +100 damage maneuvers, and I personally wouldn't care if I couldn't get all of them.)Like I said, this build is ameteur; this use of Legacy Champion continuing Master of Nine is nodoubt useful and can be abused to greater effect by someone with more experience than I.
So, who wants to get cracking?