(Explaining, Expanding, and Tweaking the "Tunnels and Trolls" magic system.)
The Game master is definitive. The rules are frequently inaccurate.
--RPG Rule #0 (with apologies to Douglas Adams)
If T&T had had an explicit design brief, back in the early days, it would have been something along the lines of, "Keep it simple, and trust the Game Master to fill in any details he needs." The result was a game that was easy to learn and fast and fun to play, but also a game that was much better suited to solo and one shot play than to extended campaigns. This is not to say that campaigns can not be run with T&T; many successful campaigns have been T&T based over the years. But T&T asks more of the Game Master than some other, more detailed games, and leaves much of what goes on behind the world's surface open to speculation.
Now, I am something of a compulsive interpolater. I look at T&T, and particularly the T&T magic system, and I see many hints of the way things work beneath the surface. Having seen those things, I can't help trying to visualize a more complete, cohesive whole, and having visualized THAT, I can't help but go back and look at the published material and see small changes that would make the whole thing more cohesive to the image that the rules implied.
What follows, then, is my effort to present magic in the world of T&T in a fashion that stays true to the original spirit and flavor of the rules, while at the same making the world feel REAL (for certain peculiar values of real).
T&T 7.5 (hereafter simply, "The Rules") uses at least three different definitions of "WIZ" pretty indiscriminately. This makes my task more than a little difficult, so I am going to try to clear that up a bit.
Henceforth, therefore, the following definitions will be assumed:
Kremm: Magical energy. The stuff that makes spells work.
Kremm Point (KP): An amount of magical energy, specifically, the minimum amount of magical energy necessary to have any magical effect whatsoever.
Current Kremm (CK): The number of KP available with a character's body at a particular moment. This number will decrease when the character casts spells, and will increase (within limits) when the character rests. Certain spells cast on the character will also effect CK.
WIZ: A character atribute which is more or less permanent (to the extent that any character attribute is permanent in T&T). It states the default value of a given character's Current Kremm (CK), in Kremm Points (KP). For a well rested character not under the influence of any spells, CK=WIZ.
A well rested person (or creature, or monster) with have a CK value equal to WIZ. A spell caster who has recently performed magic will have a CK of less than WIZ, which will be recovered at the rate of one KP every ten minutes. It is also possible (through use of the Creme de la Kremm spell, for instance) for CK to be greater than WIZ. Extrapolating a bit from the CdK spell description, we can assume that such a "supercharge" will decay back to CK=WIZ in an hour.