Group Spellcasting Ability

Okay, I keep getting ideas for this, despite my opposition to the classing and non-unique tropes.<br /><br />One thing that you can't do in many spell-casting games is get a group of spell-casters together to perform a spell that they couldn't otherwise perform individually. Basically, the group increases the spell level, success rate, strength, distance, and/or number of recipients of the spell.<br /><br />Just a thought.