Overview
Acheron converts Nihility debuffs from allies into Slumber stacks on enemies. At 9 stacks she enters the Nirvana state and can use her Ultimate multiple times per turn. She does not use Energy — her Ultimate is charged entirely by ally actions applying debuffs.
How to Play
Build a team with at least two other Nihility characters. Let allies apply debuffs (Shock, Wind Shear, DEF Reduction, etc.) to charge Acheron's Slumber. When Slumber hits 9, activate Ultimate for massive Lightning AoE. Use Basic Attacks during Nirvana to maintain damage output.
Optimal Rotation
Open with Nihility supports applying debuffs → Acheron Basic Attack to gain Crimson Knot → Skill to detonate debuffs → Ultimate when Slumber reaches 9 → repeat Nirvana burst window. Do not build Energy Regen on Acheron — it does nothing.
Strengths
Highest burst damage in the game when fully set up. Ignores Energy economy entirely. Dominates Pure Fiction and multi-phase boss fights. Scales massively with investment.
Weaknesses
Requires specific Nihility teammates — cannot solo carry without debuff sources. Slow ramp-up on single targets. Weak against enemies immune to debuffs or with high Effect RES.
Investment Priority
E0 with Fall of the Aeon S5 is enough for MoC. Prioritize Pioneer relics and CRIT stats. Signature cone is a large upgrade but not mandatory. Level Ultimate and Basic Attack first.