I've modified this addon https://www.curseforge.com/wow/addons/energy-watch-v2-fan-update for working with Death Night class in WotLK Classic.
Original writer: SeTec42
EnergyWatch is a mobile, configurable Power bar that tracks Primary and Secondary resources for every class (mana, energy, rage, etc). You can also enable a secondary bar to display your character's Life in settings!
Chat commands:
- /ew lock : Locks Energy Watch bar's position
- /ew unlock : Locks Energy Watch bar's position
- /ew config : Open addon config menu (also found in Addon tab in Blizzard's Interface menu)
- /ew reset : Resets bar scale, alpha and position to defaults
Isenbeck - Benediction-US