Just tried it. My unfamiliarity with the area showed, and I ran two full circles around the map before finding the last few mobs. Not knowing where the popups are led to one Stone Rain using Shockwave right on top of my party, killing the two hardressers.
Considering the number of avoidable popups, I don't think a straight /age is a good comparison. With strong play, mobskipping and avoiding popups, a time of maybe ~18 minutes might be doable without requiring mercenaries.
Considering the amount of physical damage in the area Illusion Mesmers might be usable but I've got a strong aversion to ever using them (go figure).
J

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