For those of you who play 40k or Warmachine, you should already understand the concept. While there are certainly no end to the legitimate gripes concerning the former game, formations are one of the few things they've managed to get right in recent years. For those who don't know what I'm talking about, a formation is an element of design space that uses list building considerations outside the normal upgrade paths to balance out possible benefits. Consider some of the current ships that require "fixes": the design space for implementing those fixes is becoming narrower and narrower, with the possibility of becoming redundant with preexisting fixes. To wit, there are only so many combinations of titles and modifications that can be implemented to reverse the bloated point cost or lack of value of current ships. So, what I'm advocating is a new kind of card that is attached to the list as a whole, rather than independent ships. Restrictions would be list based ("must take X number of Y ships," for example), and would provide a benefit to any and all ships in that list that match the given criteria.
If anyone is confused, here is an example of a formation card I mocked up:
Formation: Elite Defender Squadron
Cost: 1 point
Restriction: Your list must include at least two TIE Defenders.
Benefit: All TIE Defenders in your list have an increased pilot skill of 2, and an Elite Talent slot if they do not already have one.
Edit: As an aside, formation cards would have the added benefit of increased potency in epic matches, where some serious TLC is required right now.
Edited by WonderWAAAGH