So Fiddle now has a damage ult that roots him, getting stunned/moving/silence ends the damage, and there's nothing stopping from people walking out of range of the ult?
Tip of the day: His ult is roughly 150 Seconds, your Flash (that you should have) is almost on the same timer.
The result? You can flash out as soon as fiddles lands his ult near you.
Another solution? Stack MR and his ult wont hurt as much. Another solution? Grab a Banshee's veil and he can't fear you, and simple run out of range, since fiddles is so damn slow.
This is where I'd like to say: Learn to play.
That is all,
Not everyone uses Flash (I have it unlocked, but have others that are more useful); stacking MR then takes away from other things you may be needing instead (atk dmg, atk spd, AP, etc.); Banshee's isn't such a bad idea, though it'll only take out the first spell cast at you, so he can just waste something else.
Also, you guys seem to be putting Fiddle in only 1v1 situations. Most of the time, he'll have someone else with him (ex: Malphite, with his ult), or will jump in the end from the side. Obviously, good tactic. Again, not trying to dismiss stuff like this. However, my whole issue is the idea that he can cast other abilites (namely Fear and Crows for control) while his AOE ULT is going off. Stunned from someone else, not a problem; just have to deal with that.