Any suggestions about possible major or minor magical foci related to ignem? This is for a crusading/wizard warrior Flambeau magus.
Also, is the distinction between major and minor foci limited to subject matter range of the focus or does it encompass the bonus calculations?
Light (major)
Fire (major)
Creating fire (minor)
My 2cents.
cold, darkness, heating
Minor fire elementals
Minor Ignem wards
Ignem wards as a minor ? Ward is already a minor... can't see the point there :s.
Actually I was thinking protection from Ignem in general but I was in a hurry.
From "Magi of Hermes" is the Major Focus in "Magical Fire", any effect that creat a fire taht attack, any Muto Effect and similar with fire like objective is Major. Burn should be then Minor, but part for Natural Fire, that include CrIg to make burn or heat.
Since Cold or Shadows are Minor, Why Light or heat are not?
IMO light is very broad. With this focus, i have made some pretty usefull spell. I don't think it's suitable to be minor, because it's too broad: taking all light in your hand is ReIg, creating false sun, CrIg, Transforming moonlight to sunlight is MuIg, Make a building dark for a month is PeIg...
So... Bright should be diferent then from Light o make the diference betwen light types... but Make rebuke shadows is CrIg and Create Shadows is PeIg and so... maybe that shouldn't be minro that then.
Hi,
I might consider Light to be a minor focus. No lasers. 
Darkness, definitely minor.
I would probably consider heat to be a major focus, but cold to be a minor focus because of the way Ignem works. (There's no such thing as cold, Hermetically, it is an absence, so the Form is far more limited when dealing with it, whereas a focus in heat includes all of cold.)
Anyway,
Ken
And to think...
Focus Power from Faryes and Magical Beings are normaly limited to two Combinations of Form or all The cniques under a limited aspect, like Some or similar. That should be the limis for Magica or Potent Magics Minor/Major. I think.
A Minor Focus is "slightly less than a Te/Fo combo" (or words to that effect), so yes, if it were "defense against fire" (which can cover several Te/Fo combos, but all narrow end effects), that might be approp. (Note that "Creating a barrier of stone" or "breathing water" would not be approp imo, even if they fit the definition on some sophistic level.)