Yes, I hadn't even thought of Templar, but since it is charisma based, it would be a nice match with sorcerer in a true necro build.
There are, however, some drawbacks to this arrangement:
First, it delays by two levels entry into true necro (between the one level longer the sorcerer takes to get to 2nd level spells and the 4th level acquisition of turning by the templar). That probably doesn't matter much in the long run, but in the short run that means two levels longer to get to 9th level spells, which might be significant in some modules. (In a wizard/cleric combo in which tn requires knowledge of 2nd level spells, a character would have to wait three levels longer than a regular caster for 9th level spells; this build requires a wait of five levels on the arcane side--sorcerer would get their one level later anyway, and one more base cleric level is added.)
Second, templar domain spells get cast like bonus domain spells, not like regular domain spells (in NWN/PRC terms; I understand in PNP there is no difference). That's a nuisance, but certainly not the end of the world.
Third, and most important, the templar spell list is far more limited than that of a regular cleric. Aggressive standbys like flame strike and storm of vengeance just aren't there; nor are healing standbys like mass heal--or even regular heal--and resurrection. Templars do have some advantages: two martial weapons proficiencies, better skill points than a cleric, better variety of class skills than a cleric. None of those seem like good trade-offs for a caster build, where the cleric's more extensive and powerful selection seems like a much better deal. If you think about it, the much reduced spell list reduces the importance of dual progression. Dual progression gives some substantial disadvantages at early and middle levels, in exchange for full proficiency with two spell books at epic levels. A templar build wouldn't entirely eliminate this advantage, but it would certainly reduce its impact. In a high gold module, it might almost be better to play with a cleric that doesn't progress past the tn entry point or that doesn't learn new spells after a certain point because wisdom isn't high enough but can at least cast the full range of cleric spells from scrolls. A templar can't cast storm of vengeance, for example, at all, and I would take even the low level scroll version over a 40th level power word: blind any day.
Right now I'm playing a wizard/cleric/true necro. If one can survive the early stages, taking lich (level 14) and then demilich (level 24) gives stat boosts that compensate (at least in terms of spell power) for the fact that I have to divide my stat increases between intelligence and wisdom. I chose to get intelligence up first; natural wisdom won't hit 19 until about level 30, which means my cleric is still casting the really high level spells from scrolls, but I would rather be able to resurrect a henchman right away, scroll or not, than have to wait for the next visit to civilization to do it.
In the build you are suggesting, natural charisma would end up being much higher, so that might be a great choice in a mod in which social skills are important, especially since the templar has all three social skills as class skills. For mashing up enemies in combat, though, the wizard/cleric blend looks better--if you live long enough to fully develop it.
(Inadvertently I'm turning this discussion into something that should really have been in the character build thread--my bad!)
