Originally Posted by Amatzikahni
FoN and BV are tank items that require you to be a threat in order for the enemies to focus you. If you're bad at positioning, you may need these items; otherwise, you should do much better using that gold for aura-based items that help your team out as long as you're alive. I prefer Locket over Randuin's because your team usually has a Randuin's by that time and Locket helps keep your carries alive longer without forcing you to butcher your positioning.
I could only see this build working if your team lacked tanks/initiators, but usually you won't have enough gold to get halfway done with that tank build meaning that you're still not tanky enough for the teamfighting that occurs in the midgame. If you've already finished five items, then you should use your gold for Oracle's and Elixirs while continuing to spam wards. If you still maxed those out and have 3k gold in the bank, then somehow the game has lasted way too long and everyone should have full builds and ~70 second death timers meaning that the next fight should determine the winner.
Well as I said this is a tank support Janna build, tanky items are needed to be tanky. Yes they are expensive, and as I stated before my games end 80% of the time when I get to Randuin's Omen, often my team does not grab it so me grabbing it is good. I do get Oracle's did you read?) and I get about 15-20 wards by then. No. Joking. I get the gold masteries, gp10 items and seals and quints to help me. WITH a tank the initiation is SO great, makes no sense and can very easily win a teamfight. This is indeed a funny build but it works so well I'm positive in wins vs loses and I play about 70% of my games as Janna, only a bad team makes me lose if they can't focus whoever I'm shooting up. It is OP and I am certain of that! Try it yourself and if you have a good experience with Janna (I know for sure I do) and are used to contributing without damage, you will make your ennemies rue you.
Edit: Oh and don't forget, you are not at all tanky until mid-late game, don't do anything stupid before then and you could easily end up 0 deaths 1 time oracles for whole game.
Edit 2: Funniest, best bait in the game for sure, better than singed because most people know not to chase him. People focus you, you back of when half, shield ally for extra 50 ad, slow and laugh, heal up in 15 seconds, restart. XD