Here is the full list of all 13 Mr. Healer achievements.
Rescued the Orc Clan
Survived a battle with the White Knight
Unlocked your hidden potential
Defeated the Dark Serpent
Defeated the final boss
Defeated the Phoenix
Defeated the Demon King
Defeated the Dread Knight
Became champion of the Bronze Arena
Became champion of the Silver Arena
Became champion of the Gold Arena
Reached level 30 as any class
Have all friends reach Rank 3