Scaling spells with multiple casters ?

[:1]Here's an idea for casting targeted AOE spells.
What if the spell scaled with number of casters you have selected ?
Say, a basic fireball, you select one caster, you'd get a somewhat impressive show of force.
but if you select a dozen of them, they'd all channel the spell and you get a huge boom.
This make caster units easier to manage, IMO. It wouldn't work on single target spell like magic missile. But it's possible to give all spells AOE variant. For example, if you have one caster selected, the heal spell would target a single unit. When you have multiple caster selected, the spell gets a template and would heal everything the template touches.
Just my 2 cents.|||yes I agree with that.|||I'd prefer spell casting to be something i wouldn't have to worry about microing at all really.
But if they have to have spell casting as spells you have to use manually, then i would prefer this method.|||I am suggesting this as an alternative to auto cast. There should be option to select a spell and let the caster do their thing. but if you really want to cast a spell at an exact location, this should be the way to do it.|||Or maybe just certain powerful spells will need to be targeted and this would be perfect. So if you have multiple "experimental mages" you can group them and their nuke spell will increase in size and show the damage template.
But i'd like most spells to just be auto cast, kind of like heavy artillery.