Ruzhan, "10% more damage for each damaging Skill you've used Recently" how does it work?

Need more information for a build Idea. It doesn't seem to specify needing "different" damaging skills for it to work so I'm guessing spamming one skill would also work? If that's the case then where do crossbow bolts fit in with that definition? does continuously firing a full clip of bolts count as one use of a damaging skill? Is it per bolt fired, is it per button press, or per reload?

yes, we need a confirmation!