[3.5] Ninja / ? (Help!!)

[Kaiyanwang]

If you really want to keep Ninja/Monk you need the feat Ascetic Stalker from Complete Scoundrel. That lets you keep your Unarmed progression and keep pumping ninja up.

I would then go Ninja 16/Monk 4, I think that should do you just fine.

Second this. Some Monk bonus feat can be useful for ambush feats. I'd suggest to check Crystalkeep and/or Complete Scoundrel to find things like disemboweling strike or headshot, or staggering strike from CA.

And BTW, he asked advices for a Ninja/Monk, not for a swordsage. I expect to see in the future someone asking advices to a Swordsage built, and people answering "roll a Swordsage instead" fo a respondent conditioning (originally posted by Ivan Pavlov).

A well played Ninja is fun and can makes enemies explode by damage output, if well played. Simply, has not "click this to obtain effect" powers like the swordsage, you have to invent your strategy.