How do you treat the multiple rolls of prismatic spray?

[holywhippet]

With prismatic spray you have to roll a d8 to decide which ray or rays affects each target. Then, for most of the rolls, you have to roll for damage. Do you roll 10d6 once and use the same result for all damage effects? Or do you roll separately for each ray that hits? If the latter, what about the empowered metamagic, or the cutting words ability? The former allows you to use up to your charisma modifier in damage dice rerolls while the former can reduce the amount of damage from those rolls. But if you roll separately that reduces the number of options for rerolls or damage reducing. Even more so if you roll damage for all rays and then determine which hits who.

[lunaticfringe]

I have always seen/ruled rolling damage once, and the d8s determined the damage type. It's less time consuming that way, you can hit a bunch of targets with a well placed spray.

This also makes Empowered & Cutting words more effective with regards to the spell I think, by virtue of affecting all the beams.