Correct on the attack boost. How do I increase?
Start with the basic fighting trio - Zeus, Cdm, and CoA. I realize it's too late for you now, but you probably should stay in EMA until all three of these are at least level 10. That with the other small boosts you can get from event buildings, towers, etc, should put you at 150-200%. Then start levelling them up.....and up......and up.
How did you get to 15M points without an Arc?