Elixir slow down coat

Just a random idea;

Maybe its cool to have a coat/oil/liquid you can draw on the grass outside your base.
the coat is to slow down enemies spawning on it, maybe have like a 2-3 lower speed when they walk on it.

funded with elixir as a way to burn through elixir easy, and example cost of 5.000 per grasstile.
could also make it upgradable to increase slowdown speed.

Thoughts?

i think its bad because it is only to defend ur village, how about attacking others? it will be hard and most time we cannot win a battle because of this