You probably aren't doing the mechanics right. I never see randos do that boss right. If you're group is spread out and doesn't give a fuck about positioning you're doing it wrong.

• All range should be on the opposite side of the room as the boss. This ensures Blade surge places the image on that side of the room
  • Ranged players should be 6 yards from each other.
• When the boss casts slicing maelstrom The range should move to the other side of the room, away from the images. After it is over range should return to their side of the room to keep images spawning over there. Be sure to not be near the boss either as he also does the AoE.

With volcanic I would recommend all range except the healer to stay in melee range of the boss. This allows the healer to be the sole target for Blade surge and Volcanic allowing the DPS to stand still and burn the boss. and since you all should be doing the mechanics properly there should be very little to heal so the healer should be fine moving so much.