Idea for Teemo's Mushrooms

EDIT: Just to clarify, this is to prevent Teemo from destroying you with his mushrooms from miles away. I've experience walking through the jungle to get to another lane, nowhere near the enemy team, and getting killed from repeatedly walking into consecutively placed mushrooms.

I think everybody has had the unfortunate experience of playing against AP Teemo. His mushrooms do an insane amount of damage when Teemo builds full AP. An ADC just has to step on 2 mushroom while at 90% health, and they will be completely deleted. This is hard to play around, due to the fact that his mushrooms are completely invisible, do tons of damage, slow you, and do damage over time.

Here is my suggestion:

(1) Keep everything the same when a player steps on the first mushroom.

(2) If a player steps on a second mushroom within a timeframe of about 7 seconds or something, then that second mushroom will deal reduced damage, maybe as much as 50% less. This will prevent people from being destroyed by something they can't even see.

(3) HOWEVER, in the place of the missing damage, instead apply a debuff to any champion that steps on a second mushroom with 10 seconds. This debuff could be something like 25% reduced armor and magic resist. In addition, if the player steps on a 3rd mushroom within 10 seconds, this debuff will stack. What this will do is make it easier for the enemy team to physically burst that person down, as their health will be reduced, they will be slowed, taking damage over time, and their armor and magic resist will be very low. However, it will prevent unfair deaths that can't be avoided. This method also encourages smart mushroom placement that will lead to consecutive hits on targets.

(4) If the a player doesn't step on a mushroom for about 7 seconds, the original damage will still apply.

Please give me feedback on my idea. Thanks!