Imagine an item that completely counters your ultimate

That would be pretty dumb right? I mean who would even let that in the game?

But it is the game, and it hurts teemo. I don't get why the red trinket should also prevent his shrooms from exploding. I understand you need a way to see the shrooms so there can be counterplay, but the fact that it completely cancels his shrooms is ridiculous. That doesn't benefeit clearing shrooms, it just benefeits removing his entire ult when you fight him. At least rengar/kha are still untargetable but teemo is completely countered by it and his ult is made useless. An unnecessary nerf to a relatively weak champion.