That's right, but this feat is just an example for the DM, it's not even a real feat.
Anyways, that was no more than a side comment...
I think the "dual-class" spellcaster isn't that overpowered. You lose quite some caster levels and acces to high level spells. The great many of spells you get in return are very nice... but you still only get to cast them one at a time.
Two lvl 5 characters make mince meat out of a 10th level thuerge, while a 10th level "single class" caster drops those two lvl 5 casters in one fireball.
A 10th level MT has *5th* level spells, if you allow that feat... How will those 5th level chars deal with 10d6 (<- Practiced Spellcaster) Flamestrikes and Greater Commands, exactly?
at high levels you miss out on the punch that the highest level spells can deal.
Indeed, that is the price to pay for the breadth in spell choice and high number of spells per day the MT enjoys.
Still casting 1 spell per round...
...as everyone else...
...and it matters a lot if that spell can be a lvl 9. In my experience the power curve of spells really goes up fast after level 5.
It most definitely does, tho that is quite consistent over all levels. The jump to 3rd level is a rather big one as well. Overall every spell level roughly doubles the power level of the previous one.
The MT/TN will gain access to 9th level spells from both cleric and wizard eventually, IIRC, the true necromancer has alternating levels in cleric and wizard for the first 4 levels in the PrC and after that they proceed to advance simultaneously for another 10, right?
So, a cleric3/wizard1/MT10/TN6 (at 20th level) has the casting ability of a 17th-level cleric (caster level 20th with Practiced Spellcaster) and a 15th level wizard (caster level 19th with Practiced Spellcaster), that's 9th level divine spells *and* 8th level arcane spells! At 22nd level only, both will have 9th level spells and then for another 6 levels they will advance caster level simultaneously.
How is it not broken to spend only 5 levels total to gain the full range of 1st thru 9th level spells of another class at that level?
Bye
Thanee