The Runesmith prepares spells by enscribing runes, runes which can be cast by other PCs. My question is what happens to the runes at the end of the day? do the cease to be magical? Or are they more permanent like scrolls?
He prepares spells as normal, except that instead of readying the spells in his mind, he readies them in the form of runes.
Nothing about this description says that the runes last any longer than a prepared spell ordinarily would, so it would be “as normal”—nothing in particular happens at the end of the day, but just like prepared spells would be lost when spells are reprepared, so too would old runes lose their power.