Lord Thane why shouldn't such a kingdom be able to cast a TS?
They absolutely should be able to cast a TS!
But lets use math and logic to determine what seems appropriate.
If the spell threshold is low like the lowest spells that require 5:1 with completely teched out Elves to do, we'll begin with that.
Now Elves have a 15% casting bonus, so lets remove that since the kingdom isn't Elf. That means that at 1:1 schools, with the same exact land and ks so that there's no added difficulty, this should require +15%. For simplicity sake we can use 100 land. At 5:1 that would be 500 wizards, plus 15% which is 575 wizards. This is for a player with Magical Instruments already finished.
Now if said kingdom did have that ridiculously high of a school ratio, at 5:1 schools, then they would be casting at 115 wizards to effectively land that spell. Now if the kingdom they are casting on is double their ks, and double their land, it should be 4x as difficult.
So if the player had 1:1 schools, fully teched out, and the player was 2x their size, 2x their land, it would require 575 x4 wizards (assuming the difficulty scales proportionately with the kingdoms for fairness sake). This makes the total 2300 wizards required.
So if that KD was 5 times the size, and 5 times the land, then 575 x 25 would be 14375 completely teched out magic wizards at 1:1. Now lets add in the resistance
For a dwarf with 40% resistance that would require an additional 9583 wizards, totaling 23958 rounded down. For a gnome that would be 35% resistance so an extra 7740 wizards rounded down totaling 22115 wizards.
If he had 5:1 school, that would drop it down to 4423 wizards vs the gnome, rounded down.
Now this is all under the assumption that the spell breakpoint is that of the lower end spell, GC with a 5:1 casting rate. If it were a mid spell with a 10:1, then multiply all these figures by 2.
Of course that isn't how the spell has been working, so I used equivocating scaling in order to keep levels fair and flat.
So Yes, I agree that smaller kingdoms should be able to cast TS and succeed, they just need to use proportionately more wizards to break that threshold.
And on another note,
Lord Thane I like the idea of making it more accurate with more wiz used
I love this idea, it seems to make sense to me.
Anyway, let me know what you think! I welcome criticism, and try to be fair. So if anyone sees a flaw in this please point it out.