Alzrius
The EN World kitten
Their "home base" is their private demiplane. Needing to sleep doesn't count for much when you have bound devils protecting you. Or when you can just open a gate to the Abyss in their barracks after scrying on the place. Or any of a hundred other options that a 20th-level wizard has that a couple hundred 1st- and 2nd-level fighters don't.So if the army is stupid enough to send all their men in fireball formation (or meteor storm formation) it's not going to end well for them. But let's say they send a squad every hour on the hour. It won't take that long for them to wear down the PC, it's a simple numbers game. The wizard has to sleep sometime and they only cast fireball* a dozen times a day. I mean sure they can teleport somewhere (maybe, in my campaign they could potentially smuggle in someone to cast a spell that could stop that), but then their home base gets ransacked. Rinse and repeat.
The cheese is baked into theAll of the arguments that a wizard (or sorcerer) can take over the world relies on a massive amount of cheese that I would never allow in my campaign that let's them somehow amass an army that has effectively no cost. I just don't buy it.
...actually, no, it wasn't the point. The point, or at least my point, was that high-level characters are always a political consideration. I'm not sure why your responded back with "no, a high-level wizard can't take over a kingdom!"