I have heard that Intelligence increases spell power and that Resistance increases the power of healing spells. However when I first read this I was confused if that meant the resistence of the castor or castee. I also believed that both intelligence and resistence increased the power of healing spells.
Intelligence - Increases magical attack power and accuracy. [...] Resistance - Gives 70% of magical defences, and boosts the amount of health healed from a healing spell. Also boosts the 4 stat boosting spells.(Shield-Defence; Braveheart-Attack; Magic Boost-Intelligence; Magic Wall-Resistance)
However, initially Clerics have a higher INT stat that RES! The above quote seems to mean that intelligence is useless for clerics unless you plan to give them combat spells. Is it useless for Clerics?
Bonus: Anyone know exactly what the healing spell formula is?