BXDMG (WIP): Mounted Combat

This is something I've had in a working form for nearly a decade, and as I've been cleaning up text files on my phone (where I tend to put my BXDMG thoughts/notes as I have them), and finding myself with some time yesterday to work on this, this is where I've ended up (for now). 

As a reminder, any sort of "00" page number reference is for when this gets to layout. The "Animal Training" rules referenced here can currently be found in Fang, Faith Legerdemain. 

Mounted Combat

In order for a mount to be ridden in combat, that mount must be trained for combat (see “Animal Training” on p.00). A rider may attempt to enter combat on a mount not trained for combat; however, the mount must succeed on a Morale check before moving to become engaged and during any round that it is already engaged. The check must be made before the mount’s movement for the round and, if it fails, the mount will immediately flee at full speed to a safe distance. Mounts trained for combat need only check Morale if reduced to half their hp or less and only once per encounter.

During the movement phase of the round, mounts go last. A mounted rider must defer all their movement for the round to their mount in order for the mount to move during the round (regardless of distance), unless the rider is mounting or dismounting, each of which requires 1 round during which the mount must remain stationary and the rider may take no other actions.

Only one-handed melee or ranged attacks may be made by a mounted rider during a round where the mount moves, unless the rider and the mount are trained for “free-rein” handling (e.g., as a class feature, and possibly limited to a specific weapon or weapon type). Otherwise, the use of attacks requiring two hands, can only be made from a mount during a round in which the mount has not moved. If a rider untrained in “free-rein” handling attempts a two-handed attack during the round in which their mount has moved, they must save vs. paralysis or fall from their mount, taking 1d6 damage in the process.

Spellcasting is impossible from a moving mount, but magic items requiring only one hand and a command word (e.g., wands and rods) may be used. 

Melee attacks by a rider on a mount vs. an unmounted opponent are subject to the following modifiers (based on the angle of attack):

• Unmounted opponent is smaller/lower: +1
• Unmounted opponent is same size/equal: ±0
• Unmounted opponent is larger/higher: –1

Melee attacks from an attacker on foot against a mounted opponent suffer a  –1 “to hit” penalty against the rider but not the mount. Furthermore, an exact “to hit” roll strikes the mount if the rider is the intended target, and vice versa.

If a mount is slain, the rider must save vs. breath or be thrown from the mount, taking 1d6 damage and and being laid prone. On a natural roll of “1” on the saving throw, the rider is trapped under the mount, taking an additional 1d6 damage in the process. Freeing a trapped character requires a successful Open Doors roll from an assisting character (the trapped character may not free themself). On a successful save, the rider remains upright on the slain mount but must spend 1 round dismounting if they choose to move on foot. 

When a mounted attacker strikes a mounted target with a natural “to hit” roll of "20" using a melee weapon longer than 3’, the targeted rider must make save vs. paralysis or be knocked from the mount to the ground, taking 1d6 damage and being laid prone. The save suffers a –1 penalty for each additional 1’ of weapon length (–1 for a 4’ long weapon, –2 for a 5’ long weapon, and so on).