Dance of Death - "[Campaign 9 - Mission 2]"

I just finished a battle with the boss, and it took me two tries to beat him and get the achievement. The first time, I messed up and killed all the liches too early, before they had fully restored the dragon’s health. The boss seemed quite easy, but that’s probably because I was given a decent army for the fight, and my Sandro was also pretty well-leveled. I cast regeneration on my troops and used a weakening beam and a debuff spell on the dragon. I had fully upgraded my dark magic skills, plus I had the Dynasty weapon that gives a +5 strength bonus to dark magic, and the dynasty’s special ability, which gives a 5% bonus to dark magic. So, the debuff spell reduced the dragon’s attack by 58%, and the weakening beam reduced its defense by 34. So, I didn’t have any trouble. By the way, I noticed a funny bug: during the battle, Sandro had an artifact equipped, something like “Order’s Clock,” which reduces morale by -3 each turn, and for some reason, it was affecting the liches too! It made me laugh a lot :D
Screenshot attached:)