Here is the full list of all 36 Atonement: Scourge of Time achievements.
Defeat Ronard and his assistants without Elleria or Gashrun getting K.Oed.
Defeat the (first fight with) Chimera within 6 turns.
Complete Act 1 with Nail’s team.
Complete Act 2 with Nail’s team.
Complete Act 3 with Nail’s team.
Complete the game with Nail’s team.
Complete the game with Nail’s team on Challenging difficulty.
Complete Act 1 with Elleria’s team.
Complete Act 2 with Elleria’s team.
Complete Act 3 with Elleria’s team.
Complete the game with Elleria’s team.
Complete the game with Elleria’s team on Challenging difficulty.
Hunt down the Chimera in the woods.
Locate the Man-Eater plant and destroy it.
Bring Lasarg his lost bow.
Infiltrate the Promgan slave camp and defeat its leaders.
Find the missing man in the Medias tunnels.
Acquire the rare Nihil Blade.
Sort out the plagued rat problem in the Capital.
Find and lay to rest all the tormented souls in the Capital.
Help Denshor village with the bandit problem.
Liberate town of Vesar from a powerful despot.
Convince Ignis to stop killing people.
Let Gashrun confront the challenges of the Shrine of Phantoms.
Send Lomgorth’s spirit into the afterlife.
Find and read all the journals in Fort Caskell.
Find and defeat the giant on Mt Cereus (as Nail’s team).
Gain access into the locked room in Lomgorth’s Tower.
Teach Sugel a lesson.
Have Kanden reunite with his girlfriend.
Defeat Rick the Despot on Challenging mode.
Defeat Lomgorth’s golems on Challenging mode.
In the final battle as Nail, vanquish the Past avatar first.
In the final battle as Nail, vanquish the Future avatar first.
In the final battle as Elleria, vanquish all avatars one by one.
In the final battle as Elleria, ignore the other avatars and vanquish the source of the problem.