I wrote about a possible ninja class for some time already, i’ll leave my vision of it to you here in case you didn’t see it already 
I see ninjas as fast and specialized warriors but also great spellcasters. They should be excellent weapon masters but only with their trademark weapons like katanas, sticks, short swords, kunais, and throwing weapons like kunais and shurikens. They should possess also some good martial arts abilities and evasive or illusion skills like clones etc. And also a good amount of elemental spells typical to the ninja’s japanese folklore, maybe even some spirit summoning from their rich folklore.
Trait - Intonjutsu (or Concealment) it’s a ninja special ability after their training to be highly aware of their surroundings and be able to evade physical and spell damage when entering a fight for a short amount of time. Increase their evasion rate by 30% and reduce spell damage by 30%. Extend this bonus by 15% to the allies. It’s active for the first 5 seconds when entering in combat, and resets after 5 seconds of being out of battle.
Energy type - Chakra, is a spiritual and physical energy mastered only by ninjas. It grows by evading attacks or by doing trademark generator magic spells. Out of combat it grows slowly.