FLASH is a commonplace .. EXHAUST is usable for ganging and so.

These Masteries are for high damage and defensive game. Fiddlesticks is a paper hero, so with him it's needed to play defensive and carefully

Most important stats for FIddle are magic penetratin and ability power. Mp5 isn't so needed at Early game, there is always a chance to get blue buff.

Fiddlesticks is a good midder, but liner too. Always keep last hittin' minions and try hit enemies with E from max range, the cost of mana isn't high.

Fiddlesticks is a nice ganger with R from bushes, if it is not warded, so try always surprise your enemies and help your teammates.

FIddlestisks's R is the most important spell in late game, so try to keep always on no cooldown. Try to stay behind your team or anywhere in the bush near your mates. Wait for the start of the fight, when enemies get lower hp and then cast that to the middle of the fight. Be ready to use Hourglassr if enemies are attacking you and before they stun you, because it's hard to stay alive when you are in the middle of the fight.