"Preferred Fixed Keys
Fixed Keys core to Nikketa’s function are:

02-01 - Righteous Doll: This key gives Nikketa 1 Confectance Index after any of her skills, including when her Ultimate is activated through her summon’s counters. This will allow her to Ultimate more often as well as dealing extra damage for any excess Confectance Index she has.

02-03 - Messenger of Justice: This key bumps her stability damage by 2 for any targets afflicted by Guilt, allowing her to get through enemy stability faster and punch through any cover or stability-based mechanics.

Fixed Keys of contextual relevance that supplement Nikketa’s core function are:

04-03 - Just Desserts: Skill 1 now generates Tideway tiles, giving Nikketa a means of applying Hydro weakness for all the damage amplifying effects it provides.

06-03 - Oppressive Air: Gives Nikketa the ability to source her own Attack Up II self-buff. This fixed key tends to be made redundant by the fact that teams try to plan around having a dedicated Attack Up II buffer, but her ability to self-buff can still be valuable in less optimized setups."

Stern gaze seems like it'd be really good against powerful targets. Does it flat out not work on bosses?