Hi there. KaiserLos here with another blog :D
I'm sure you're all very aware of this, but ever since his rework, Heimerdinger's getting a lot of attention. A lot of people used to underestimate him. Then some summoners started playing him ('cause why the hell not, right?) and figured out his playstyle, and discovered just how powerful Heimer really was. Heimer is an anti-diving champion that relies on his turrets for safety and damage; during the laning phase at least. Now, there's a significant number of Heimerdinger players especially after the Visual Upgrade. And a lot of mid-lane champions are struggling to lane against him because once you get too close, he'll stun you, shoot his rockets and take lots of damage from one (or both, or possibly all) of his turrets.
But there are a few champions who can either counter him, or simply lane against him with minimum difficulty.
Now, I only know two of them. But there are probably more.
First up is Ziggs. Ziggs' abilities are all AoE. With it, you can spam your bombs from a distance and maybe destroy a turret or two. I played as Ziggs and laned against a Heimer once, and I easily kept up with his own farm. I had to make sure I had enough mana regen to spam my skills, though. So I started off with 2 Fairy Charms and some potions. With that, I am actually able to both poke Heimer and his turrets.
The second one is Syndra. She has a lot of AoE as well. But what makes her counter Heimerdinger is her ability to displace. With either a Q-E combo or a Force of Will, she can easily place Heimer's turrets into an unfavorable position.
That's all I have for now. If you have any more counters to Heimerdinger, feel free to share them in the comments below :P