Say, I was playing for 8 levels with Wis = 9 and Cha = 19. From 9th level and further I'd like to get them swapped: Wis = 19 & Cha = 9.
What are possible ways to do so? There is the retraining feature in the DMG, but it has house rule smell and requires cooperation from DM. Is there any other more straight methods to swap two ability scores?
I'd like to give example for similar process in the other field. You could swap feats known with retraining, that is rather cloudy process. And you could swap them directly with Dark Chaos Feat Substitute.