Attraction Spell - Prioritize Your Targets

As the title says I'd like to add a new spell to the game.
What it does is that it is dropped as a normal spell, but in a smaller area of effect which affects only one or two buildings. The buildings who have the spell applied to them are automatically focused by nearby troops.

I use this picture for example:
http://i.imgur.com/mhqQR40.jpg

I need to destroy the Air defense as fast as possible, but to that I have to destroy the other buildings in front of it. To surpass this I use the "Attraction spell" on the Air defense which makes it the prioritized by my dragons who senses the "Attraction spell" within a certain area.
The spell might be overused so my thought is to limit it to require 2 or 3 spaces in your spell inventory.

Thanks for reading and please leave feedback. :)