Pick your most comfortable champion. If you can't play any AP champions dont feel forced to pick one and then feed because you dont know how to play them.
Also there are a lot of armour pen items
so dont feel like you immediatly lose when you get a full ad comp.
With the exception of cleaver, suggesting those items while in a full ad comp is literally the worst advice you can give.
These items grant flat penetration. Contrary to %pen, flat penetration gets weaker the more armor the enemy team's stacks. What this means is, in a scenario where the enemy team is already bound to stack armor, you're really shooting yourself in the foot building those items.
While is is a good idea to only change an intended pick of the other pick is someone you are equally comfortable with, it is not a good idea to not have any mages you can fall back on. Annie is 450 IP, and is incredibly simple to learn how to play. Pick up at least her of you really need an AP pick (not to mention that there is usually at least 1 AP champ on free week at a time)
