.....you're cheating if you don't build only recommended items and in the order in which Riot placed them.
*Zed dies in a 1v1*
Zed: "Enjoy your ban"
Vi (me): "What for? Out playing you?"
Vi: "The hell you talking about?"
Zed: "You bought Guardian Angel and it's not your last item, the rules say you can only buy it as last item"
Vi: "Zed, I don't care about your silly rules, this is ranked and I here to win"
Zed: "They aren't my rules, they are Riot's rules and you broke them, enjoy your ban cheater"
Note: He did not break my GA in that 1v1, he ulted me, I Q him as he lands, ult him back and he dies.
Tho technically, even by his rules I wasn't cheating as we won right after so I didn't got buy other items thus making it my last item.