if both spells are cast together in the same instant, both mages would be in a protected window, in which every save for fire is made automatically...
if you look at bg 2 in verbose mode, I noted saves being made when you trigger sunfire. so i figure sunfier is actually delay blast fireball triggered at YOU, and the spell also makes all saves for you automatically, so no damage is taken to caster. so if two mages cast simultaneously, and I've seen sunfire take out CLAY FRIGGING GOLEMS, most magic resistatn thing in book, the over lapping areas of effect get seriously nasty. think 4 mages, and you have a winner, here!! move mages into position around enemies, best in a crowd!!!
then have each mage trigger sunfire!!!! fighters have some nice armor, like gorgon plate that will give them fire immunity, with ring of fire control for mazzy, and ring of fire resist for jahiera, and red dragon plate, they can reach 100%...so they are just watching 40 or so troops,in tob, get vaporized!!!!
so i tested out, using my pc sorc kensai and sweet aerie, who looked really wide eyed and got all trembly just before we went out to face shadow dragon....she could handle the dragon part, but did not like the sound of "experiment" one bit,,,,
so we went out, cast together with shadow dragon between us, both of us well within each others blast radius. pause, then cast.....all i heard was shis shriek and aerie was removed from party!!! total chunk, as she was literally vaporized by my triple spell triggerd sunfire....each sunfire was 15d6, so at maximum damage 90 per wave, around 270!!!
darn, I saaid, back to drawing board....
remembered my pc had robe of vecna!!!
loaded up triples again, was in middle of edwin quest, and tried taking the robe off....not a scratch!!! both aerie and pc survived!!!!
so with 4 mages, at points where each mages fire blast will over lap, anywhere from 150, reasonable per mage, if I overlap a dragon, I could hit him with over 600 points of damage!! if ambushed, I could kill the group of monsters surrounding me instantly. party would be invulnerable!!!
i cant remember if you can take armor off your character during battle, I know for sure you cant put it on...
funny, fav item in the game, for so many people, can become liability in certain tasks...
is this not elegent????party ambushed? in watcherskeep, if you get surrounded by heart seal gang, more than a serious possibibilty, just have your main mage, move away from blast area, as he has robe of vecna, most likely edwin, or pc sorc, then have all secondary mages trigger saved spell triggers at once. warriors are safe via items from red dragon and underdark, or your less protected warrior has used ilbratha, hmmmm...i think mirror image will protect you!!! pretty sure, as it protected random encounter low level mages from dragon breath, they got stunned, but not dead...
so have warrior cast mirror image with ilbratha, good sword, excellent loot, and you can have each mage cast mirror image too, via contingency spell, wait half a round for it to take effect, then unleash hell, or just have secondary mages, all with same casting speed, trigger while main mage moves away to attack a more distant target...
a spell effect so elegent it actualy takes casting speed into account....
so before encounters where you are likely to want ot blast everything away, have main mage switch to alignment robe, by this time you should have them, and make sure warriors have enough protection from fire. walk in, get the obligatory monster dialog, and microwave them to death!!!
in fact, for some situations, you might even want to have each participant cast increased acuity to clean tehir aura so each mage has the identical casting speed!!!
is this not elegeant