Guild Wars 2

Stealth isn’t restricted to one sense, aka sight as in this case. Stealth is avoiding all of whatever senses might detect you, so it’s perfectly logically to exploit the dredge in this manner by means other than sight.

You have not known tedium until you’ve tried to destroy structures with a condition necro. But it makes flavorful sense. As a mage specializing in the forces of life and death, what kind of power can I wield over an inanimate trebuchet? At least golems and steam creatures have some kind of magical spark that can be approximated as “life.”

That being said, an elementalist (or guardian) should be able to burn those trebuchets down. Fire does not care if you are alive or dead. Fire only cares if there is sufficient oxygen and if there is a sufficient temperature (with some limitations on material composition, fine). And magical fire can drop the latter. So yeah, I’d like to see some burning vulnerability for structures. I guess chill holds to the same rules, but it isn’t DOT, so it’s a bit less important.