The New items for mages. Or just meta.

Okay, lets talk about the new mage items or meta. I like going mid lane usually when I am in solo queue or sometimes bot, this could be because I'm not used to the new mage items but I feel like its not strong enough to deal with the new meta like one time when I went against a galio mid and I was doing fairly fine but then I get out-scaled with barely two items by 30 min. Now I was decently farming and an even score but I was never able to kill the galio cause he had so much health and around the 20 min mark he did more damage than me. Now let me tell you going against a as should be fine but no because he could just keep hitting me with q and killing me every time he gets close. Cause he had a and when I had and so he had more health and damage ._. while he was the main problem they also had and who were out scaling me already. So idk if its how I built ahri or if I just played bad idk just help me figure this out.