Here is the full list of all 13 A Healer Only Lives Twice achievements.
Defeat Golem
Cure Petrification or Poison by using items or skills
Enter Tier 3 (MAIN Mode or EX MAIN Mode)
Game over
Learn all skills
Attack three enemies at one time by using Courage skill
Defeat Troll Thug
Defeat Minotaur
Defeat Gryphon
Unlock all upgrades
Complete MAIN Mode or EX MAIN Mode
Complete TRIAL Mode
Complete EX MAIN Mode