Buff her by doing the following
- If a target has at least 3 Crimson Knots debuffs on them don't tick down
- Crimson Knot stacks limit per ability usage is raised to 2
- Maker her breasts bigger
- Increase E1 Crit rate to 28%
- Change E2 completely. Make it instead give 55% EHR to all Nihility characters in the party, and any excess of EHR over the amount necessary to guarantee is converted into % vul at a rate of 3:1

There. Acheron is now good, makes other Nihility units good and is a proper debuffer.