But then I realized that it wasn't just eccentric, it was potentially profound; I realized this when I thought,
“What if every damaging spell used the Magic Missile Mechanic?”
My first self-objection, 'what is the justification?', led to me concluding 'it is when a magic-user gains access to a new level of spell.' Wow! OK, that makes a lot of sense; when a spell caster gains access to a new level of spells all the spells he knows become more powerful/effective.
To try to keep things clear in this post I am going to use 'level' to refer to class level and spell level and 'rank' to mean 'the maximum possible spell level a particular magic-user can cast' so, for example, a 5th level magic-user would be 3rd rank because he can cast 3rd level spells. Got it? Good!
So let's tweak Magic Missile just a little bit so that it says this,
'the caster gets one missile per rank; each missile does 1d4+1 damage'.
OK, that is still largely the same; a 1st level mage gets 1, a 5th level mage gets 3, but an 11th level mage only gets 5 – the 6th only comes at 12th level, when they get access to 6th level spells. This is a very small difference that I think most people can live with.
Now, let's look at Fireball; we change it so that instead of saying,
'Fireball does 1d6 damage per level of the caster',
so that it instead says,
'Fireball does 2d6 damage per rank of the caster',
and suddenly a 5th level mage casts a 6 HD Fireball – after all, he's 3rd rank!
If we use this mechanic it means that for a lower level magic-user his damage leads (i.e., a 7th level mage casts an 8 HD Fireball, but still only does 8 HD at 8th level) while for higher level mages the damage trails (a 12th level magic-user does a 12 HD Lightning Bolt, but so does a 13th level mage). This is a minor advantage to low level spell casters and a minor disadvantage to higher level spell casters, a combination that I feel means 'still balanced'.
You can expand this to all sorts of spells – the degree of change with Enlarge, the weight capacity of Telekinesis, the size of Wall spells. Apply it to range and duration and you have made a very minor tweak to virtually every spell, adding a nice little bit of flavor to the game without really changing much of anything in the rules!
It also has a few interesting implications, doesn't it? It sounds like damage spells (and maybe a few others, too) 'max out' at the 9th rank, meaning you get no more than 9 individual missiles with Magic Missile while Fireballs and Lightning Bolts never do more than 18 HD unless something odd is going on. [Suddenly Death Knights are even scarier!]. And what about that magic-user henchman with a 9 Intelligence? He maxes out at 4th level spells – does that limit him to 4th rank forever? Does that mean a magic-user with a maximum spell level of 5th (i.e., maximum of 5th rank) can never do more than 10 HD of Lightning Bolt, even if he makes it to 16th level?
Put this into a campaign and a few things happen. First and foremost, high stats become just as important to a mage as to a warrior. A fighter with a 12 Strength is fine, but the advantages of a 17 Strength are obvious. With the Magic Missile Mechanic in place suddenly the difference between a mage with a 12 Intelligence and another with a 17 is just as clear. While I have never bought into the 'linear warriors, quadratic wizards' belief in OD&D. AD&D, etc., if you struggle with this in your campaign the Magic Missile Mechanic can tamp it down a fair bit by limiting the power of the majority of your mages.
It will also impact magic items in your campaign – 12 HD Wands are suddenly an even Bigger Deal than before! You can add a class of magic items that add to the effective rank of the caster; some for just range, others for duration, a few for everything, etc. In the end you can really add a distinctiveness to your game without really changing much at all!
What do you think?