naaaa there are so many things you (and me) dont know
here are some things i red recently - i have a bigger list but im to lazy to search now:
try to find the thread "tipp of te day" or sth there is ahuge amount of little tips you never heard about (ok some are wrong but anyway)
Naga Song of the Siren can be used to initiate a teamfight from half the map distance -it can also be used to sleep 4 opponents in a teamfight and focus the carry that just used bkb or has linkens
Repel can be casted on a useful way on opponents to prevent certain buff or heal spells
Treant can use spells in Nature's Guise withtout being revealed
Some people tend to forget that purge removes God's Strength, Overpower and Repel
-> its more the usage of abilities wich has unexpected potential!