Combat

Physical Attack

Physical Hit Ratio Defense Ratio

Magic Attack

Adjusted Level = Level + Rebirth Level (max 140 in total)
Mage Level = Adjusted Level / 10 (round result down) 
Circle     = the circle number of the spell you are casting
Penalty  = {   5,   5,   8,   8,  10,  14,  28,  32,  36,  40 } 

Magic Hit Ratio

Base Value = Magic Skill

if Magic > 50, add
   Magic Bonus = Magic - 50

if Circle < Mage Level, add
   Level Bonus = 5 * (Mage Level - Circle)

if Circle > Mage Level, subtract
   Level Penalty = b - (a / c * b) (round result to nearest)
   a = Adjusted Level - (10 * Mage Level)
   b = (Circle - Mage Level) * Penalty{Circle}
   c = (Circle - Mage Level) * 10

add Hit Ratio bonus from items and talents
multiply by percentual Hit Ratio bonus/penalty from talents

Magic Resistance

Base Value = Magic Resistance Skill

if Magic > 50, add
   Magic Bonus = Magic - 50

add Magic Resistance bonus from items and talents
multiply by percentual Magic Resistance bonus/penalty from talents

Chance to Hit

Probability [%] = Hit Ratio / Magic Resistance * 50

Magic Absorbtion (?)

Base Value = Sum of Magic Absorbtion bonuses from items and talents

if hit by elemental magic (fire, ice, earth, lightning),
   add respective Elemental Absorbtion

Spell Damage (?)

Base Value = Base Spell Damage
multiply by (1 + 0.003 * Magic)
multiply by percentual Magic Damage bonus from talents
add Magic Damage bonus from items

if crushing hit, multiply by Magic Crush Damage

multiply with target's Magic Absorbtion