Originally Posted by Xyirx
1.) Use wards. Sight Ward for 90 gold is enough to save your whole team.
2.) Use stun/silence. These should ruin Fiddlesticks who channels in brush.
3.) Use knockback. Gragas, Tristana and Janna does well in countering Fiddlesticks' Crowstorm.
4.) Get Banshee's to avoid being feared in Crowstorm.
Low level players usually don't even know wards exist, but as you move up you'll find people always use them (if they don't have something like Teemo's shrooms or Nidalee's traps doing the job already). Against certainly enemies, such as Fiddle, the value of wards goes up tremendously. (Fiddle not only jumps out of nowhere in team battles, though that should surprise no one, he is also very likely to do some jungling and go for Golem on both sides of the map, which you should not let him just get freely.)
It gets to the point where players buy Oracle's just to kill wards, in some games.