MedeaFleecestealer: Sounds like you might not be up to date with the game version. 1.1.9.7 is the latest one.
"Granted Skills
Conflagration (Granted by Item)
Unleash a piercing beam of pure flame so intense that not even the toughest armor can withstand it. This is a channeled skill and must be held down to maintain. At 100% Cast Speed, Conflagration deals damage and drains Energy every 0.3s.
208.3 Energy Cost per Second 0.3 Second Skill Recharge
220-270 Fire Damage
1266 Burn Damage over 3 Seconds
+35% Crit Damage"
Channeled skills will always use a lot of energy.
If you're not using the granted skill and still seeing this happen verify/repair your game files. If it still persists then please report it as a bug here
https://forums.crateentertainment.com/c/grimdawn/bug-reporting/27 I do have the latest version but it is patched. Ill redownload the offline version and reinstall at the latest version of it, instead of patching it to date.
Updated Reinstalled completely. Checked it. Relic in Inventory still says 50 mana cost a sec, but after equiping it and looking at the skill, it says 200. I was patched to 1.1.9.7 and now I am Installed to 1.1.9.7