vealin99 wrote:what kinds of situations would call for tankiness
Try this thought exercise:
When you get your Phage built, and when you are starting to have the cheddar to buy more items, stop for a moment and consider the situation. How many kills and how many deaths do you have? If you have no deaths, you are probably safe to buy more damage (triforce) to get more kills. If you have 10 deaths, you should probably buy some tankiness (frozen mallet) to try to stay alive.
A large part of being good at league is adjusting your build on the go. Like for example, as an adc if you have 4 offensive items and the enemy has talon and akali and you don't get a single autoattack off in fights before you die, it might be worth it to get a warmogs or whatever tank item is popular these days.