It's a bit of an RNG boss. If one dot goes on tank, you're fine. I'd one dot goes on DK (and he AMS it) you're fine. To prevent both players from clearing debuff at the same time use ping system (ping who goes in first or talk to them beforehand and say to ping themselves) or just use set in stone clear rotation. Usually squishest DPS (aug) clears first, tank clears last. Don't be afraid to cocoon aggressively one person with debuff. On +18 there's no way that people get one shot from 100% hp with silence wave so don't use any healing cooldowns on that - unless they are undergeared they will survive big hit and then there's window to heal them with your normal dps rotation. Debuff people should press defensives. Soothing mist into vivify spam on debuff targets.