Dispersion

Dispersion (also known as luck) is a factor affecting damage in every Advance Wars game.

Effect
Dispersion is a damage modifier applied in all unit vs. unit combat engagements. It allows units to deal more damage than the damage readout suggests.

An example of dispersion in effect would be the following unit matchup in Advance Wars: Days of Ruin. The red and blue armies are in combat, neither side is using COs. The red team's Rocket unit fires on a blue Recon situated on a road. The damage readout says 80%, which correlates to 8HP of damage. However, there is a chance of it doing 9HP of damage instead. Dispersion is not factored in when firing upon destructable terrain such as emplacements or meteors.

Although Nell, Sonja, Flak, Jugger and Rachel are known for their dispersion rate modifiers, every CO has a dispersion rate of at least +10%, or 1 extra hitpoint of damage.

In Advance Wars 1
Rather than the normal +10%, Nell had a +15% dispersion rate. This meant that she did 1HP of extra damage more often than other COs and occasionally did +2HP of additional damage, if the unit matchup permitted. This increased to +60% during her CO Power.

Sonja was the first CO (and at the time, only CO) to have a negative luck modifier. Her units had a -20% luck modifer, resulting in up to 2HP less damage inflicted.

In Advance Wars 2
As well as her above abilities, Nell also gained a total +100% luck modifer during her new Lady Luck Super CO Power.

Sonja's weakness was also reduced and her units had a -10% luck modifer rather than the -20% luck.

Flak was introduced in AW2 and was the first of two COs to have both a positive and a negative dispersion rate. Without his CO Power he had a positive rate of +20% and a negative of -10%. This was expanded to +60%/-20% with his CO Power and +80%/-40% with his Super CO Power.

In Advance Wars: Dual Strike
Although Nell was unchanged between AW2 and AWDS, Sonja and Flak were both changed, mostly for the better. Sonja's negative dispersion rate was reduced further to -5%, while Flak's dispersion rates changed to +20%/-10%, +50%/-20% and +90/-40% during normal play, his CO Power and his Super Power respectively.

Another new CO was introduced in AWDS, similar to Flak. This CO was Jugger, who was similar to Flak but more extreme. Jugger's dispersion rates were +25%/-15%, +55%/-25% and +95/-45% during normal play, his CO Power and his Super Power respectively. Nell's sister Rachel also had a dispersion modifying CO Power, which granted her a dispersion modifier of +40% for a turn.

On top of that, force ranks were also added. One of the Lv. 1 force ranks, Lucky, added a 10% dispersion rate boost to whoever was using it. This would stack with all other dispersion modifiers, allowing all COs to do up to 2HP more damage than normal.

Tag affinities were also introduced. Each tag affinity rated with a star saw all units operating under that duo of COs receive a 5% luck bonus per star. This stacked with any other modifiers, meaning that Nell using Windfall and the Lucky ability could do up to 125% extra damage – a very strong chance of instantly destroying anything she targeted (particularly if they had already been weakened by Rachel’s Covering Fire).

In Advance Wars: Days of Ruin
Since force ranks, tag affinities and all the previous games' COs were removed and no dispersion-based COs were added, all dispersion rates were at 10%, regardless of which CO was used (if any).