It can be on the official League of Legends side view, and indeed in your Match History, then choose your opponent and you see the order in which he has geskillt what and what he bought when
I've never heard that one can stalk gaaanz exactly on 'ner separate page, what the person EXACTLY WHEN has gebuildet. I guess that you have to follow precisely ingame then probably ^^
Do you think that you can look during the game what your opponent is buying?
I know an app since it will only work with rank games
Probuild, highly recommended