Midlane itemization: AP vs AD

So I don't have any ad runes yet (lvl 29) so I'm limited to ap characters and like mid lane. Most games I'm against AD assassins like , or , and they usually have a great variety of things to build first item that give great offensive stats as well as either defense, utility, or crit.

It just feels like I have really limited play options as a mage to keep up. is too expensive and actually gives zero defensive stats until you can stack it up in 3 waves. Which is 3 waves the AD midlaner can push really hard and either roam, dive you with jungler, or just rush lvl 6 and kill you or burst you out of lane, then roam anyway. In order to keep up with how fast they can push, you are kind of forced to need mana regen, but there just doesn't seem to be a good item that gives mana regen, defensive stats, and ap as a reasonable first item.

I'm not here to qq that assassins are op or that items suck right now, I'm just here to point out patterns I've seen almost every game and really am looking for suggestions on how to play against them as mages. For now I've been rushing into on a lot of mages so you can at least stay in lane a bit more. But nothing I do is any match for these ad assassins that can waveclear instantly and then get free thunderlord procs under my tower while I farm and then just dive or roam.

Tldr: How are you other mages itemizing against ad midlaners that push super fast and then dive or roam? What playstyle is working for you against these ad mids?