NEW DARK SPELL (Rush spell)

Today i thought about a new spell named "Rush spell" .I was think about poison spell that how it works amazingly ..So by the poison spell i got idea about RUSH SPELL ....it can slow up defences and reduce the damage from it...just like how poison spell works on opponent clan castle troops.....when this spell is felt on defences the colour of defence will change into brown and work as a defence poison...It will best applicable at upcoming bomb towers....at Town hall lev 10