Most people would use a AP Sion build but I have to tell you that this build is so much more effective. Its whole purpose is to be a strong 1v1 solo to start and then a 1v3 champion towards the end. By the end of the build no one should be able to escape you. Going from one of the slowest champs to one of the fastest. As far as skills go, get enrage whenever possible. This will give you the health of a tank without any of the items. Always upgrade cannibalism when possible. Its how you maintain those 3v1 battles. Your stun is merely your initiator. The shield helps to push a tower or escape a battle.