You have 4+INT per level. Assign:
If you are interested in exploring other, perhaps more resilient, magical damage dealers, I can provide a guide on the , which combines the full arcane repertoire of a Sorcerer or Wizard with the durability of a Fighter. pathfinder kingmaker magus sword saint guide
Here is a recommended ability score allocation for a using a 25-point buy: You have 4+INT per level