New Spell Idea

Alright guys, this is my first post on this forum!!!
I came out with some kind of a new idea for a spell, i would like to call it MIRROR SPELL.
This spell is that kind of spell that you don't use on your troops, but on enemy defences.
The idea is that, for o short time, like 4/5 seconds enemy defences that are affected from the spell take the same amount of damage that deal to the players troop...
It would probably cost around 70k elixir o even 1k black elixir and take around 45 minutes to create.
What do you think about this?
Peace