Originally Posted by
gracfuldeath
Blink, goblin rocket jump, and other similar things negate fall damage by changing your character's direction of movement before you hit the ground, and it ends up forgetting that you were falling really fast and from a really high spot and resets your fall trajectory to where blink/rocket jump ends (or something like that) and so you live. You have to time these moves to sometime before you hit the ground. If you fly up 150 yards, dismount, immediately hit blink, you're still going to die.
It sounds like the intent of this glyph is to allow you to fly up any distance, dismount, use demonic leap, and charge straight into the ground safely no matter when you hit the button.
There's a difference between negating fall damage, and using an ability to change your fall direction/speed/etc to land without taking enough fall damage to kill you or do significant dmg.