When to build Rod of Ages

Rod of Ages, or ROA as some might know it, is a god tier item in the hands of a champion who does not scale very hard into the lategame when built damage alone. This item is utilized on any mage, who is very bursty, lacks utility, and needs some durability, such as my main, Twisted Fate. ROA is not on many champion's reccomended items, simply because it is not cost efficient for some champs, who may be a little difficult to farm with (im talking about you ). I know this is not a long guide, but it's for new/ bronze players, who sit there building exactly the same every game. Just trying to throw them my little knowledge. Feel free to add your opinion below.