So I've been looking into mounted combat a bit and was thinking about the following situation: an mounted enemy charges my players, they brace with spears. They are able to evade the enemy lance point with a dodge roll and manage to land a spear hit on the charging enemy.

What's the damage? Do I calculate slam damage as if the enemy slammed into a wall or something and add the spear's imp damage on top? Or is there another formula?

Also: does a lance charge on a horse count as move and attack with the associated -4 penalty?

So the magic expansion says that you can buy the formulas themselves but it doesnt list the cost anywhere?