We should still be well stocked with supplies and various consumables (scrolls, bombs, healing salve, etc). I would have Dany and Malarys expand the number of Celestial Brilliance banners from 170 to 365. There have been a couple days since the battle, so plenty of time for them to have prepared and cast the spells.
Each of them casting Chained Celestial Brilliance five times using their Beads of Karma would be enough to affect 195 more banners. With that many, there should be multiple overlapping Celestial Brilliance effects blanketing the entire Legion. 1d6 damage per round is rough on Undead, especially lesser ones, but 2d6, 3d6, etc., is even worse.
[X] Crake
EDIT: Ah, I see you were already ahead of me,
@Crake. That's what I get for stopping to eat dinner.
I think if we're going for overlapping over the entire army, 410 total, which is enough to have the effect active on every Company's banners or just about, should do the trick.
That should mean that the active AoE damage should generally be at least 2d6, around 3d6 for line companies. So low HP critter should generally melt away in front of an advance within a couple of rounds, as they enter within range of the Celestial light, they immediately get hit for around 10 HP on average, and for a heavy infantry Legionnaire in formation, they'll generally hit for around 14 average damage further w/Magic Army up, or 28 average on a crit.
Quite frankly, rat swarms aren't tanky enough to deal with that kind of consistent damage, and their AC ain't shit either. A green Legionnaire should have around 80% chance of hitting, with a veteran around 90% chance. Even assuming half damage gets dealt to swarms, heavy infantry are great at hitting adjacent foes, it's their entire doctrine. I don't expect most swarms to last more than 2 rounds. Which lines up, since they would need at least 4 rounds to kill a green soldier, and 5-6 for more blooded troops. Combine that with healing magics...
One bit of bad news is I don't think we can easily heal the Strength damage except with time, but they can just continuously cycle soldiers by ranks, switching positions as soon as the first set of rats dies, then shifting them to the back of the line for triage.
Moreover the banner effect should extend
outward by a large amount of distance, so a tide of rats doesn't work either--they will quickly die even as the front rank is killed against the shield wall before they even get there.
Since the basic tactic seemed to be fighting around the feet of their foot soldiers, I expect generally they will hold back an appreciable amount of them instead, just continually sending forth waves of rats to make sure there's at least one wave of them massed against the shield wall harassing their ranks.
HOWEVER.
That means that a rat wave needs at least two rounds to make contact with the Legion if they hold back beyond the range of the banners. So they get hit at least once by the aoe effect without doing anything significant to our forces, then again in the following round. Then two Legionnaires clean up, again within an average of two rounds. Since average undead aren't that smart, if we target officers directing the unliving human wave tactics, that means they'll generally bunch up more, and thus evaporate in the aoe instead of dying in waves.
Basically the enemy KdR ratio, which is how they're hoping to achieve victory, is predicating on the idea they'll be able to maintain control on probably at least 100,000 to 150,000 stupid thralls, ghouls or skeletons. But how are they to do that if anyone vaguely competent looking is being bombed from outside the effective range of their own siege weapons or mages? They can't. So their goal quickly shifts from "drown them in bodies" since inertia is on our side there, to killing hero units to demoralize the army.
So basically we just need to not die... easy, right?
