How to charms reform
0. Pour milk at Duvessa.
1. Make charms permanent-until-dispelled, like rmsl/dmsl. (it hurts, I know)
2. Spellcasting success % is the % chance that a charm will NOT be dispelled when PC is hit.
3. Throw 2 eggs at Duvessa.
4. The above % chance is your current % spell succes chance (so armour makes it more likely that a charm gets dispelled on hit.
5. Spellpower determines only charm strength - it doesn't determine length as there is none. Regeneration nerf, yay.
6. Mix Duvessa with slime Dovan.
Step 4 ensures that permanent charms are not abusable by the remove-armour-and-cast-before-combat one secret trick duvessa doesn't want you to know.