Anti-magic metal

[RS14]

The problem, as I see it, is that both SR and army size increase linearly as a function of wealth. Caster level increases linearly with level. With wealth increasing exponentially with level, you can give an army SR: enough.

For example, assume it costs 2000gp to field such a soldier. At 5th level, you can field an army with SR 4. Not terribly effective. But by 10th level, you can field an army with SR24. By 15th level, an SR of 100.

Of course, this will be slowed by characters being unwilling to spend all their gold on soldiers. This is reasonable. But the growth such a system as presented is still fundamentally unbalanced.