There's a bug with this addon in 1.6.7 and the Adept prodigy. It goes something like:

- Get the Adept prodigy
- Use a category point to increase a category's mastery, and you'll get a .6 improvement: The .2 is mutiplied by Adept's x3 instead of being simply added. (So if your category was 1.0, Adept increases is to 1.3, and improving the category with a point increases is to 1.9 instead of 1.5.)
- Now remove the category improvement, which you can do with FlexSpec. I can't remember the exact result, but it decreases by .2 or something like that, so now your example category from above is at 1.7.
- Improve the category again with the point you just removed, and once again it increases by .6, and now you're at 2.3.
- Repeat for infinite category mastery.

I believe this bug also exists if you have already improved a category prior to taking Adept, but I can't remember how it plays out. (But it's a variation of remove category point, add it back, and repeat.)

I may have gotten the precise numbers incorrect, but if you try it out, it's pretty easy to reproduce. To verify this is a bug with FlexSpec and not T-Engine, I disabled the FlexSpec addon (via desc.lua) and didn't have this issue (both with adding a cat point post-Adept or removing it on the same screen).

What does it do?