Ahri is very squishy and requires survivability with the build that you have drawn up i can see that you thought about it a bit but you are missing the intial tankiness that she needs to survive EG a Rod of ages or an abyssal scepter. The banshees veil is a good idea albeit wont save you from most of the cc an enemy could push on you. If you take a Zhonya's what about the summoners who dont use items actives?, all you get is a bit of armor and ability Power. Instead you could opt for an archangels that gives more damage, I like the idea of a void staff but then you could opt for different boots. Like Mercs or even ionian, the cdr or tenacity could make a difference in survival or death. Just wanted to let you know you could push this build further, Don't stop when you are done explaining. Explore some more and see what makes a difference. Also add more detail to you're descriptions.