Tips against Fiddle? Oh you're asking me to ruin my entire lane haha. Alright here is what I got for you.

Fiddlesticks, when played the way I have guided, is very ward heavy. Once you get your support item built there is going to be trinkets and pinks everywhere as well as his passive when it's available. Sadly there is not much counter against this except to have a lens yourself and try to clear the wards I place. Common places would be dragon pit, bot side river bush, any of the bushes in bot lane, bot side jungle bush, and middle river bushes. Other locations sometimes are just middle of the jungle to catch vision of the enemy or possibly to scare them into thinking I'm close while we take dragon.

I often see people walking up to my passive, even when I'm dead, and getting spooked into wasting some mana. This needs to be avoided at all costs. You really think that the Fiddle is going to wait for you to enter the bush before I run away or flash? If I really was in that bush and alone: I'm going to be fearing you. No fear = I wasn't actually in that bush. Don't fall for a fake flash.

You need to be building tenacity to reduce my fear. Mercury's Treads is really the only item you can build for this and possibly Sterak's Gage but you need to have it activated to get the reduction on tenacity. Sadly, even if you get this item: you are either going to be losing out on your actual boots to help you or wasting a slot for an item that you won't even get off before I fear you.

Your next bet is CC. Fiddlesticks is garbage if I'm CCed. I can fear but only once. If a sup and adc or in a team fight I am done for. Lux, Morgana, Blitz all have good, long CC that can reduce me to nothing if you get one good stun off.

Fiddle relies very heavily on magic resistance early and becomes a secondary tank late game if you get there. You need to build MR as much as you can to combat this. Only issue there is while you were focusing protecting yourself from my ult and such, I feared you whole team back into my team and let them finish you off.

Your last bet is to be smart as a team. Fiddle sticks needs to gank to be good. I gank my own lane after sitting in alcove for a few seconds and people still fall for it. You need to get good vision on spots I can jump over the wall and fear you into someone else. Expect it when you're pushing tower and my team is behind it trying to defend.