Guild Wars 2

I posted this in general HOT since I don’t plan on using the rune with a scrapper, but figured you guys might be well versed in how it works:

Has anyone done much testing on what is and isn’t affected by rune of the scrapper? First I assume it’s only direct damage, which is fair. But my question is how the effect works, I assume that any source of direct damage, provided that the unit responsible for that damage is within 600 range, will be reduced by 7%?
For example, A guy casts a ground aoe at 900 range that deals 1k a second, and approaches you as it ticks. When he gets within 600 range, does it drop to 930 a second?
Additionally, I’m particularly interested in its applications for raids. Has anyone used these runes on Vale Guardian and confirm if things like the ground AOE in the later phases are reduced by 7%? Or is that a separate source of damage (not VG) so it doesn’t count? Or is my assumptions of how the rune works off entirely?