I’ve posted this elsewhere, but If you’re running warlock, try bottom tree stormcaller, getaway artist (if you have it), and risk runner. Risk runner does the deed more consistently than nova I found. It’s practically a mini stormcaller. Target red bars, chain damage to orange bars and then finish them off, generally ignore the yellows as the take too long to kill. Pop and arc soul (either normal or super) before sailing into battle for that bit of extra damage. Works best with fallen or cabal as they will proc arc conductor for you. I think I got about 6-7 of the medals using risk runner and stormcaller. (To be fair, risk runner would prob work with any roaming arc subclass. I just happen to main a warlock)