code:

ATTACK TYPE (HEX: 06) (Magic Attacks, Light Staff, Staff of Judgement)
1) Aegis Shield Check (6.3.2)
2) Use Magic Damage Parameters (6.4.1): 
   Attack = Spell Attack + (0..(Spell Attack/8))
   M = (Level*Magic Power)/256 + 4
   Defense = Magic Defense
3) Apply Multitargetting modifiers to Attack (6.5.1).
4) Apply Target Status Effect modifiers to Defense and M (magical) (6.5.10).
5) Apply Magic Element Up modifier to Attack (6.5.14).
6) Apply Attack Element modifiers to Attack and Defense (6.5.16).
7) Damage = (Attack - Defense) * M.  Max Damage = 9999.


6.5.1) MULTITARGETTING MODIFIERS TO ATTACK

If targetting multiple Targets, Attack = Attack / 2
Spells that automatically target all targets do not suffer this penalty;
the exception are Rods that are used as Items; they DO suffer this penalty,
even the ones that automatically target all targets.