Um, I don't know about full detail, but I'm pretty sure it prevents the affected ninja from doing combos and sets characters like Ino up for certain jutsu.

Tezu: now, I'd like to say that'd be obvious, but if it really were obvious that people who I just SET ON FIRE shouldn't be able to do jutsu either. So.

Thank you all! No matter what it does, I now know it's worth it to upgrade Shikamaru, at least for Ranked Battle/Survival Trial. ^_^