Here is the full list of all 20 Urtuk: The Desolation achievements.
Win the game
Win the game on Exploration difficulty
Win the game on Adventure difficulty
Kill 250 enemies
Reach the Ruins
Kill Amos
Kill Turgul
Kill Mandoralen
Kill Ivadd
Kill Victor
Reach the Underground
Reach the Swamps
Win your first battle
Start Urtuk at least once!
Win the game on Veteran difficulty
Win the game on Epic difficulty
Win the game on Desolation difficulty
Kill Andur
Achieve the Champion trait
Defeat all leaders of the Shattered