Unfortunately this will have to wait until GW3. This is a limitation of technology as the engine can't handle the strain of of anything more than 5 targets per AoE. It's the reason all of the 10 man skills were phased out last year.
I seem to remember ANET mentioning that balance changes would be more like "shaves" or "hair cuts" rather than deep slashes. That was a few years ago, but obviously that changed sometime in 2021 or so.
I want this, but when worn on the back and detonated in an enemy zerg it immediately puts 5 enemies (regardless of how many boons) within 360 distance into downstate.