These are the rules Dan came up with for Lion Rampant:
Artillery
Use 1 artillery model plus 6 crew (Your Leader can't be part of this unit).
May be operated so long as 1 crewman is still alive.
Points cost: 4 points (maximum of 1 artillery piece per Retinue).
Range: Anywhere within line of sight on the tabletop.
Shoot value: 7+.
Damage: Roll 12 dice against the target unit, hitting on 3+. Ignore cover.
Reload value: 10+. After a successful Shoot action, the artillery may not be fired again until a successful Reload action has taken place. This is carried out as a normal, ordered activation.
May not move during the game and must be deployed in the player’s deployment zone.
If contacted, shot at, and for Courage tests, the crew count as Serfs at their current strength (6 models or less).
The crew must maintain cohesion around the artillery model (not moving more than 3” beyond it).