I know how inner might works and i don't mean the free cast every 60 seconds but the UI of the ability saying it costs no energy to use the ability.
I have found this is the case for multiple frames:
Chroma: Spectral Scream
Garuda: Blood altar and Bloodletting
Hildryn: All abilities
Hydroid: Tidal surge
Inaros: Scarab Swarm
Ivara: Quiver
Limbo: Banish (only on prime, not in store)
Revenant: Enthrall
Saryn: Spores
Titania: Lantern
Vauban: Minelayer and Bastille
Wisp: Reservoirs
Xaku: The Vast Untime when in loadout, The lost when looking via store
