The situational section isn't in any order. Pick the most relevant to the enemy's team. Heavy AD? Rush your thornmail, sunfire then randuins. Strong AP then grab a spirit visage and/or Banchees. If against a teemo I always build a Banchees as it mostly removed the threat of his shrooms.

I recommend always going for a sunfire though.

My might feel it necessary to sell your talisman at some point as well which is viable, however I almost always don't because I love the utility that it provides, from chasing people down to escaping situations, and even in teamfights sometimes.