Here's an example spell if anyone can spot anything wrong with it. The only thing I don't know how to calculate how many ranks the magic skill should have. Does anyone know how to work that out?
Acid Arrow
Create acid
Cost 7 MP; skills evocation 0
Casting time two actions
Duration instantaneous; range 50'; target one creature
On a successful MAG vs DEFENSE check the creature takes 2d6 acid damage. On each subsequent turn the creature takes 1 additional point of damage for 4 rounds unless they wash it off with about one gallon of water or wipe acid off itself with two actions, though this usually ruins the scraping implement.
Costs 3 MP range, 4 MP damage.
Acid Arrow
Create acid
Cost 7 MP; skills evocation 0
Casting time two actions
Duration instantaneous; range 50'; target one creature
On a successful MAG vs DEFENSE check the creature takes 2d6 acid damage. On each subsequent turn the creature takes 1 additional point of damage for 4 rounds unless they wash it off with about one gallon of water or wipe acid off itself with two actions, though this usually ruins the scraping implement.
Costs 3 MP range, 4 MP damage.