IT seems the summons are all Tai/Nin Damage and they're all based on your main character's attributes. I've got all purple/blue ones but honestly I can't be bothered testing them one by one just to see how much damage they do - they seem to do roughly the same amount, but as a Blaze it's hard for me to tell since Ignited targets take bonus dmg and I would have to really pay attention what goes on when.