I think this needs to be properly checked as I'm confident (but not 100%) that I caused damage to others during artillery. It was hard to tell as warcraft logs doesn't seem to log who caused the damage correctly under 'problems'. However, I cloaked mine 2 seconds before landing, I successfully avoided all damage but everyone else in the raid got hit by 3 artillery strikes (3 people had the debuff). This tells me that you don't prevent the raid wide damage. Hoping someone can confirm.