Post: #4

spell effects can be changed based on your .ini settings. If MAGICF_OSIFORMULAS setting is disabled on your sphere.ini, sphere will use the EFFECT value set on spells (sphere_spells.scp) so if an spell like Heal have EFFECT=8,12 it will heal a "random" value between 8,12 (lower magery skills have more chance to get lower values, higher magery skill will get higher values)

otherwise if you use MAGICF_OSIFORMULAS, sphere will ignore these EFFECT values and use the internal OSI formula instead, which are more complex because most of these formulas are different from each other, they get the result based on combination of skill values, etc

and as already said, you can also use LOCAL.Effect to customize these effects or use your own formula on scripts