I'm asking this question for a 3.5 game, my question is relevant to PRPG as well.
Let's say a PC just acquired this spell. They can deal 15d6 fire damage with the spell.
1) Is that PC supposed to roll 15d6 individually for each 10' cube?
2) If you position 4 of those cubes so each affects a Large+ creature, do they also affect it individually?
These questions came to my attention recently, when a fellow PC took out a Frost Giant Blackguard 8, and his squad of 6 Frost Giants, and a large White Dragon on his first turn. We were 13th or 14th level =/