Children of Zodiarcs

Can be missed.

In mission 19, you're going to be tasked with staying alive for 11 turns against waves of bulky guards and adept healers, and Zulta who's a range healer with incredible healing stats. But the goal of this achievement is to kill Zulta specifically before the end of the 11th turn.

Best strategy is to bullrush your way to the back of the map. Use Xero to keep Xero and Brice healed up because Brice is quintessential to surviving this mission in general considering she's a walking, talking glass cannon, but especially against Zulta. Nahmi is best when she's spread out so all three units aren't vulnerable at once, but don't hesitate to send Nahmi over to back up Xero if Brice is taking a licking and you can't manage to pull heals from Xero or Leech from Brice. You can (probably) survive a single turn of everyone clumped together to save Brice.

As for killing Zulta, I guess any damage can technically do, but I found it easiest to use both of my Devour cards (Brice) in one turn on him (make sure she has a bunch of star dice), and use one of your massive AoE attacks (Burning Anger and Burn Burn Burn of Brice's work best I've found) that cause Bleed and he should die as soon as the turn is over because of the stacked damage.

Best of luck!