Now, that alone would be far to powerful, so I came up with a hook: the source book states that for each TD at least one material component is needed. So the generic TD checks the casters inventory for valid components and presents a list accordingly. If you've got a dragon's tooth, you can summon Kreb?s Flaming Dragon, but if you're out of bones, well, tough luck, no Kolin?s Undead Legion for you. Of course, when you cast the dweomer, the corresponding component is used up. That means you could implement some insanely powerful TDs, but limit their use by putting only one or two of the needed components in game

I don't know if that's feasible, having a spell interact with inventory in such a complex way. But it'd sure be cool, and IMHO as close to PnP as we can get without being too much of a pain.
Now, one thing's still missing: spell descriptions. I'd simply put them on the components, in the identified description, with a pretty high lore value (and preferably a level requirement for successful identification, but I think that's not possible).
So, what do you think?
Armin