You fell off hard in the mid game because you didn’t build any damage. You did well in lane and then mega trolled by spending 8200g on 205 AP over the next 15 minutes.

With Doran’s Ring and blue buffs, you don’t need Seraph’s, which is a god awful item now. If you’re hard carrying and ask jg for blue, they will give it to you.

If you fix your item paths it’ll make a huge difference in how much you can actually contribute.

Just think about how bad Demonic is here: you’re getting maybe 10 AP from its passive and they don’t even have a tank to make the 1% max hp damage matter at all in comparison to just having more AP.

You spent 8200g to get 205 AP in your 2nd-4th items. You could have spent 4400-4600g on Mejai’s and Shadowflame/Void Staff for 225/260 AP and a ton more magic pen (WAY MORE damage for almost half the gold spent). Once you get your Deathcap which brings you up to the same 8200g that you spent before, you’re getting 500+ AP for the same price that you were spending to get only 205 AP. For some perspective, that’s the difference between your E doing 546 damage versus ~950 damage, and that’s not even considering the early pen difference.