Terios, it's ******** simple. You'll hate both yourself and me when I finally reveal it. It's not gamebreaking, but it helps a decent enough amount.
Also, tends to do more damage consistently than fair, especially against those ******* short characters (read: Olimar, Psychic Brats, Squirtle, etc). Great for pressure strings, especially against the back of their shields.
Holy crap, thank you guys, you just gave me a new idea for a string. I'll share this, since it's you're doing, and it's not game-breaking.
His dtilt has IASA frames, which allows you to use it fairly effectively for shield pressure. Dtilt, jab, dtilt, etc. Don't do it too long/often, or you'll get punished. Since I tend to jab after nair, or utilt, or whatever, a decent pressure string would be something like:
nair, jab, dtilt IASA, jab,
or
nair, dtilt, IASA jab/jump.
Interesting.
Also, nair to dash attack is really good, and dash attack does really well against Marth. No jokes, son.