Just farm. The idea behind this build is that you become tank enough to take the punishment and make the assassin champs useless versus you. If you farm enough at full build you will have over 1000ap. My last game with it I got it up to 1400 ap, winch was great, because meant that with Lich Bane I was doing +700 dmg on an AA - great for pushing towers, doing sustained dmg in huge amounts and securing Objectives.

This is a good example: My last game with him using this build. Me and a friend ( he is the Shaco player) were premade in Rank Flex. The enemy team was 5 man premade. Hard as hell due to them having coordination with everyone on their team. As you can see this is the score from a 40 minute game, where after the 20-th minute we didn't have any turrets or inhibs top and bot.