Kaifuku Jutsushi No Yarinaoshi

“Healing magicians cannot fight alone.”
Keare, who was bound by this common knowledge, was exploited again and again by others. But one day, he noticed what may lay beyond healing magic, and was convinced that a healing magician was the strongest class. However, by the time he realized its full potential, he was deprived of everything. Thus, he used healing magic on the world itself to go back four years, deciding to redo everything…
(Source: Novel Updates, edited)