The way I could see formations work is as you say auras but more in the form of arcs of the facing for instance
Front arc of the formation user gain attack bonus
Side arc of the formation user gain evade bonus
Rear arc of the formation user gain defence bonus
what I would purpose is a class that gives bonuses based on there facing to aid other members of there party this would add the fun aspect that people need to follow instructions to get the best possible bonus in the following example.
Tank : If the formation user is a tank they will always face the monster away from there group therefore giving everyone a attack bonus due to your facing your party as they smack it in the back.
DPS : If the formation user is a dps they will be in front of all the ranged user behind them giving them an added bonus of defence and those who are melee beside the formation user gain a bonus to evade.
The aura I have in mind would be the following also each rank increases the range/stat bonus but also the sp drain rate.
Tip of the spear aura when activated aids those in front of you with attack bonus.
Shield wall aura when activated aids those behind of you with a defence bonus.
Pincer strike aura when activated aids those beside of you with a evade bonus.
Aura Mastery max rank 5
- less sp drain
- Allow 2 auras
- less sp drain
- Allow 3 auras
- less sp drain