Grenade Salad

I mean, if there are downed PCs, they’re struggling already, IMO.

You can still save the kingdom as a party full of evil bastards. Baron van Dyne can’t usurp the crown with the aid of an army of elven barbarians, because the crown is not his to steal. It’s mine.

Just like any party, you need a motivation that’s compatible with cooperation and the narrative in some capacity. The only difference is that in stereotypical ‘good’ parties, players can just default to ‘save the kingdom because it is Right’ rather than having to think about it.

An adventure for levels 3-10 and 17.

This right there? This is why nobody plays high-level games.

My group uses this, but with a separate temporary exhaustion (we call it Trauma) that goes away on a short rest. Still handily serves the purpose of discouraging yoyoing without being too punitive.