i wanna be a TF main. i like him, he have all u can ask for. AOE, CC, "unlimited" mana, good mobility. but what do you build on him? last game i went lichbane > lucidity boots (yes i know. maybe should have gone with merc instead) > stop watch (yes just stopwatch) > rage blade > deathcap
If tons of Healing on enemy team. 
If heavy MR stacked tank
Depending on situation... i dont play him really, but from what i have seen usually it is Ludins, lichbane, some boots depending on situation, Zhonyas, then you could do Banshees or gunblade or rapidfire cannon or deathcap all have their usages.
That is for AP. Otherwise AD is like a mix of Ezreal and Vayne type thing... Triforce, hurricane, boots, rapid fire cannon, GA, then you can do like IE or static or blood thirster or Bork or rageblade or something.
Main thing with AP tf is you are going for that 1 shot W and Q poke and kite thing. AD is where you want to just rapid fire your autos. But this is all depending on situation.
If anyone has anything better to add.... feel free, but figured id make a start perhaps
