|Battle of Castillon (source)
In the ratling post, I alluded to an ability to use attack ranks for things other than just an increased chance to hit. Specifically, ratlings can use attack ranks to improve their armor class on a round by round basis, with each rank so applied improving the effective AC by one armor category. Ratlings naturally have light armor (AC 7). For example, a ratling who fights at attack rank 1 may choose each round whether she wants to have AC 7 and attack rank 1, or AC 5 and attack rank 0.
Fighters (but no other class) may also use attack ranks defensively in a similar way to improve their AC from round to round. In addition, fighters may spend their attack ranks to improve the AC of companions they are defending if that makes sense situationally. For example, consider a first level fighter wearing medium armor, using a shield, and fighting near an unarmored magic-user. This fighter has AC 4, the magic-user has AC 9. The fighter has the following options:
- Fight at attack rank 2. All armor classes remain unmodified.
- Fight at attack rank 1 and improve her own armor category one step (AC 2).
- Fight at attack rank 1 and improve the magic-user’s armor category one step (AC 7).
- Fight at attack rank 0 and improve the magic-user’s armor category two steps (AC 5).
Armor class may never be improved beyond AC 2. Defensive assistance from multiple fighters does not stack. Defensive assistance may be divided between multiple companions if that makes sense. I am not sure whether or not this floating defensive bonus should stack with armor. For now it does (as I would like to see people use this option some of the time). Fighter retainers may be instructed to defend their employer. Fighters must be armed with melee weapons or shields when defending companions (not missile weapons).
This ability is similar to the defense trait from the Hexagram path of arms. I think it is a nice addition to the fighter class, giving them some ability to defend other characters mechanically without resorting to other cumbersome subsystems. I could also imagine attack ranks potentially being usable for other things too, though I don’t want to overload the system too much.