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kog needs a team built to protect him. He has no escapes, so if you get caught, you might as well turn around and auto attack. His lategame is probably the most devastating apart from karthus though.
I'd only build tear on like corki for the manamune, blitz, kassadin(mana problems), and maybe orianna(bad mana problems). On all ad carries, rushing IE is usually a lot better than manamune (except maybe corki).
If I want to troll around as zilean I might go tear->deathcap->stack AA staves...
garen is not very relevant past 20 minutes unless you feed him hardcore.
Jax on the other hand can feed like a boss early and then simply dominate past 40 if you farm up instead of suiciding mid or something. Of course you could always buy Tryndamere too if you are confident you can use that...