Greetings fellow summoners :) I've been using Fiddlesticks as my main for a very long time, and I have 300+ games with him. This guide will teach you how to jungle with him, how to kill with him, how to win with him, and generally how to be friggin' legendary with him!

Since this is my first guide, I don't have a clue about inserting pictures, and item/skill links. Will include that later, when getting more experienced.

A quick Pros/Cons - Fiddlesticks.

Pros:
Fast Jungler
Best stun in game (3 second fear, rank 5)
AOE Silence
Amazing ult
Good ganker
GAMECHANGER!

Cons:
Squishy
No escape possibilities except for Terrify.
Mana-thirsty without Golem Buff
Bad farmer
Ult takes 1,5 seconds to channel, and can be interrupted with CC.

A quick Pros/Cons - Fiddlesticks.

Pros:
Fast Jungler
Best stun in game (3 second fear, rank 5)
AOE Silence
Amazing ult
Good ganker
GAMECHANGER!

Cons:
Squishy
No escape possibilities except for Terrify.
Mana-thirsty without Golem Buff
Bad farmer
Ult takes 1,5 seconds to channel, and can be interrupted with CC.

Marks I go flat Mark of Magic Penetration, since it's the best offensive choice for Fiddlesticks, and most casters in this game.
Seals I go flat Armor, simply due to the fact that I jungle, and it really helps out in jungle.
Glyphs I go flat Ability Power, because that extra early ability power will help getting you some stacks on that Mejai's.
Quintessences I go flat Ability Power too, for the same reason as glyphs. Those 15 extra AP really boosts your drain.

In masteries I choose a very common 9-0-21. Picking up the smite bonus in Offensive and getting that bonus Magic Pen. In Utility remember to take the extended buff duration and the flash CD reduction.

In this section i'll try to explain my item path.
First I pick up the Amplifying Tome and a health potion. This will give you around 45 AP, which will make your Drain hit for 44 every second, at rank 1! That's 220 damage for a rank 1 spell!
After clearing jungle, you will want to gank. After a gank you should have around 1150 gold, for Boots of Speed, and Mejai's Soulstealer. After that you are gonna build Rylai's, which will give you some bulk HP, and making you harder to kill = Keeping your stacks.
Rabadon's Will be your next item, which will really boost your AP to insane amounts, and at this point you should be able to score a penta ;) No, not necessarily, but you should be raping faces. From now on, we need resistances. Armor and a sweet passive from Zhonya's, and Magic Resistance and a great passive from Banshee's Veil.

If you feel too squishy early game, you might want to grab Doran's Ring instead of Amplifying Tome and a health pot. This will give you good stats, but making your buildtime longer.

Additionally instead of building Banshee's Veil late-game you might want to get Abyssal Scepter, against heavy AP, and to buff his passive (10 Reduced Magic Resistance for enemies)

In this build, you should be focusing on getting Drain maxed out ASAP, since you will be able to solo almost everyone, in every part of the game. When you can't level up Drain, take a point in Terrify, which is great with drain. You should at all times pick Crowstorm, when possible. Max out Dark Wind last, because it's not the damage we want. It's just the silence, which we already have with 1 point.

Picking Flash and Smite should be pretty self explanary, since you need Smite for jungling, and Flash for, escaping/correcting that missplaced ult.

In this section i'll give a step to step explanation of how to jungle with Fiddlesticks.
Head to Golem (Blue buff) first, having your team protect you. You DON'T want to take golem first. Instead you should be taking the Big Wolf at the nearby creep camp, which will spawn by 1:40. This gives you 15 seconds to kill it, and get to golem camp, before it spawns. Clear it, with auto-attacks, and Drain. For the love of God, drain whenever you can. Use smite when it has around 445 HP. Use smite last. Always.

Now you will want to kill the 2 small wolves that you left alive. Head to Wraiths and - Dark Wind, Drain the blue, big one. At this point your health shouldn't be critically low, so you should be able to take Lizard (Red Buff), having 2 points in Drain, and 1 point in Dark wind. Dark wind it, drain it two times, and then Smite it. Take small golems, get full HP, pick up Terrify rank 1, and prepare to gank those lanes!

After ganking you will want to go back (as earlier described), and picking up boots and stacks. If you have any Gold leftover, then you should be using them on wards! Ward dragon, and ward for your team, if the support isn't capable of doing his/her job. Golem should be spawning soon, around 7:20-7:30 (depending on how first you cleared it).

Now you will want to look at the map. Any possible ganks? That enemy bot lane recalled? If you have any advantage bot, you should be going for Dragon, which will be possibly with rank 3 drain, but to be safe, get your teammates helping you. Oh, and don't do this if you have no idea where the enemies are, or without warding!

Working with the team. Mid- to lategame you will want to assisting the team with your ult. A good Fiddle ult will almost always win you the teamfight. If possible you should be standing in a bush, which will make interrupting your Crowstorm, much harder for the enemy, and it will create an element of surprise.

Terrify the biggest threat on the enemy team. AD Carry/Caster

Dark Wind the target

Drain the target

Kill the rest with AOE Silence bounce and your Crowstorm AOE. GG

Fiddlesticks farming skills are terrible. Dark Wind only bounces 5 times, and the damage isn't great enough to clear a creep wave, even late-game.