New Spell Idea!

I just posted a poll thing about a new Dark Spell Factory, now i have an idea for a new spell for that: A spell that will let you place a certain amount of troops for a limited amount of time anywhere on the map. For example you have the spell at level 1, then you'll only be able to place troops anywhere on the map but they have to take up less than 5 space things (like in the barracks when you train a giant, it takes up i think 4 spaces) so you be able to place like 5 archers or 1 giant and all that. And then with every upgrade of that spell you can higher the capacity of troops you can place! Is this a good idea?