Domains at War.

It looks like your post is dissapeared alex…(concerning medium foot moving as heavy foot).
The way the rules are written don’t seem confusing to me (albiet I’m coming from CHAINMAIL).
unrelated: The description of fireball on pg. 30, where a 6th level (6d6 dmg) mu can wipe out a host of 24 ogres still seems like overkill to me. Weighing the cost of recruiting a mid-level magic user vs. an army of ogres, I can’t help but think players are going to lean heavy on MU every time. Beyond that, fireball is leagues more powerful even than it’s sister spell, lightning bolt which–in it’s description, cannot kill more than twelve 1st level fighters! Fireball can kill 96 HD of ogres. (perhaps I’m missing something, if you could help me out) and fireball is leagues better still than a battery of heavy catapult. I’ve made this point before of course, but the wizard is much more than a walking catapult first laid out in CM, he and the dragon are an f-16 fighter dropping cluster bombs and daisy cutters.
Now let’s look at the wizard and the dragon strategically, there is never a reason to put either of those two forces into 1:1 combat against another hero, because their AOE in mass combat vastly outperforms their abilities in 1:1 (the crux of the problem–turning their 1:1 abilities into mass combat abilities). Why would a wizard seek out a hero on the opposing team, when the effects of dueling and defeating that hero pale in efficacy to the ability to blow up 24 ogres at a time? It’s the same with the dragon. Although the lone fighter has a powerful interest in singling out the enemy wizard or dragon, it is a fool of a player who buys a fighter unit instead of a wizard or dragon unit.
unrelated #2 pg. 38: I can’t quite tell on the chart, but are the elven light foot in elven chain? Is that why their AC is 3 and their mov. is 12"?

Movement Types:
As I was writing the rules it became apparent that I couldn’t use Heavy Infantry to mean two different things and have the rules be coherent. So I ended up defining the movement types as “loose foot” “formed foot” “loose mounted” and “formed mounted”. I deleted the thread because it was moot.
Fireball:
Wth fireballs’ diameter reduced from 40’ to 20’, its effectiveness in mass combat has been substantially reduced. Here’s the new rule. [Note that under the current v11 rules, being revised, a Unit of 100 1HD warriors now has on average about 8 hit points].
Fire Ball: This spell creates a column of fire that affects 1 unit within 6”. The base damage from a Fire Ball is equal to the spellcaster’s level. If the unit succeeds on a Saving Throw versus Blast, the base damage is reduced to half. The unit then takes either the base damage, or 1/8th of its maximum hit points (rounded up), whichever is less. Cavalry suffer double damage from all Fireballs. Note that 100-man units of 1 HD or less creatures will always take exactly 1 point of damage from a Fireball. Any unit struck by a Fireball must make an immediate morale check.
EXAMPLE #1: A unit of 100 orcs with 8 Unit Hit Points is struck by a Fireball cast by a 10th level mage. The base damage from the Fireball is 10 points. The unit makes its Saving Throw versus Blast, reducing the base damage to 5 points. The unit takes the lesser of the base damage (5 points, because of the successful save) or 1/8th its max hit points (1 point), so it takes 1 point of damage. Note that the Saving Throw was actually meaningless – about a dozen orcs will always die to a Fireball, whether they save or not.
So, as you can see, even a 10th level mage would now need to use 8 fireballs to wipe out a unit. His effectiveness is more akin to a battery of heavy catapults, and not an F-16.

Im confused a bit on the saving throw. If they fail the save do they still take 1/8th max hp dmg or the full 10? Is the 1/8th max hp triggered only by the successful save?

The 1/8th max damage is regardless of whether they save or not. It’s spatially impossible for more than 1/8th of the unit to be hit by a fireball.
Consider that a unit covers 60’ x 40’, or 2,400 square feet. A fireball has a diameter of 20’, so its area is 3.14x10^2, or 314 feet. Thus a fireball cannot affect more than 13% of the unit, e.g. 1/8th of the unit.
If that still doesn’t click, let me break it down step by step in the hopes of achieving better clarity!

  1. The base damage from a Fire Ball is equal to the spellcaster’s level.
    EXAMPLE #1: A 6th level mage’s fireball has a base damage of 6.
    EXAMPLE #2: A 10th level mage’s fireball has a base damage of 10.
  2. If the unit succeeds on a Saving Throw versus Blast, the base damage is reduced to half.
    EXAMPLE #1: If a unit saves against a 6th level mage’s fireball, base damage is reduced to 3. If the save fails, base damage is 6.
    EXAMPLE #2: If a unit saves against a 10th level mage’s fireball, base damage is reduced to 5. If the save fails, base damage is 10.
  3. The unit then takes either the base damage, or 1/8th of its maximum hit points (rounded up), whichever is less. Cavalry suffer double damage from all Fireballs. Note that 100-man units of 1 HD or less creatures will always take exactly 1 point of damage from a Fireball. Any unit struck by a Fireball must make an immediate morale check.
    EXAMPLE #1: A Unit of 100 Lizardmen with 20 Hit Points is hit by a fireball doing base damage 6. They failed to save, so base damage remains 6. The Lizardmen suffer the lesser of 6 or (20/8=2.5, rounded down) 2. The Lizardmen suffer 2 damage.
    EXAMPLE #2: A Unit of 100 Heroes with 32 Hit Points is hit by a fireball doing base damage 6. The Unit makes its save, so base damage is reduced to 3. The Heroes suffer the lesser of 3 or (32/8=4) 4. The Heroes suffer 3 damage.

What type of creatures would ever take 10 dmg from a fireball? A legion of 12HD Fighters I suppose. Am I wrong or will almost no one ever take full dmg from fireballs? The threshold seems so high it almost seems like a waste of ink to say that anything other than, “fireball does 1/8th the units hp in dmg every time”. Am I wrong?

Bargle, you are 100% correct. In virtually any plausible scenario the fireball would simply do 1/8th the units hp in damage. That said, it only takes a few sentences to give the full rule for those Judges who might wish to use it.
MUCH of the apparent complexity of Domains at War is because of special cases like this.