I found the answer to this a few years ago after wondering how it's done for probably a decade. Now I can't remember and can't find any trace of the thread explaining it.   On Shadows Fall's Fleshold at about the 2:37 mark, he does this rapid descending harmonics thing. I believe some other artists have used this too. I kind of remember trilling between two frets on the left hand maybe being involved. How is this done?
Last edited by xr280xr at Jun 22, 2017,
For example, use the open A  (frret "0"), 3rd frret and 5th fret.

Repeat the pattern  5,  3,  0, 5, 3, 0 ...   (hammer on the 5th fret each time.  Pull-offs otherwise).

With picking hand, lightly touch the A string ... could be your finger tip, or edge of palm.  Doesn't really matter.  Experiment with how much force you apply, as this drastically changes the sound.

Then move that point of touch (without lifting off) backwards and forwards, while continuing a fast left hand pattern.

It's very easy to do.
Last edited by jerrykramskoy at Jun 23, 2017,