The Ancient One draws power from the Dark Dimension to heal herself and prolong life. This is explicitly called the “wrong way” in the film—using forbidden magic for personal healing leads to corruption. The movie argues that healing magic must respect natural law.
Crunchyroll is the most reliable for The Wrong Way to Use Healing Magic . movies4uvipthewrongwaytousehealingmag best
If you are looking for a show that flips the script on the tired "useless healer" trope, The Wrong Way to Use Healing Magic Chiyu Mahō no Machigatta Tsukai-kata ) is a must-watch isekai gem that officially has a Season 2 in production Why It's a Top-Tier Isekai The Protagonist's Grind The Ancient One draws power from the Dark