Okay. The idea behind this is that all mages have the same spell list, and each colour has a flavour on top of that. You can learn a spell as a colour spell to apply the flavour or a generic spell to not do so.
Here are some example flavours:
Red: Add 'and does red single' or 'and does strikedown' to any offensive spell. Multi-target spells get an extra red single to every target. Weapon buffs at one level lower. Blue: Add 'blue through' to any damage. Add 'and does Repel 5' to any spell; upgrade duration of any Repel by one notch. Black: Add 'subdue' to any damage. Reduce spells by one level by adding black damage on the caster (amount of damage depending how broken the original spell is). Green: Add 'and does Halt 5' to any spell; upgrade duration of any Halt or Freeze by one notch. Freeze one level early. Brown: Reduce all defensive spells (bar invisibility, if it stays) by one level of cost. Add +1-and-colour-brown or 'strikedown' to one-shot weapon buffs. White: Self-cast spells may be shared amongst multiple participants (splitting the effect - i.e. a 4AC spell would instead give 1AC to four people). Alternatively, any self-cast spell may be reduced by a level by including at least four participants who must be touching the caster with a free hand.
Red, blue and green are obviously broken at first level as written. Can probably fix Red by 'red single at first level, may subsequantly add to any spell; strikedown at second level, may subsequantly add to any spell', and green and blue by 'status 5 at first level, may subsequantly add to any spell'.
Some time ago some more clever people than me apparently made notes on something similar to this but then the notes got lost / never materialised. I'd like to see them if they did turn up :).