Here is the full list of all 33 The Iron Oath achievements.
Win a battle without taking any damage
Kill an Elite enemy
Kill 50 Elite enemies
Kill your first Boss
Kill 20 Bosses
Kill 500 enemies
Kill 1000 enemies
Win 100 battles
Have a character kill 3 enemies in a single turn
Hire 10 recruits during a campaign
Reach Level 10 with every class
Have one character reach Level 20
Unlock all enemy Codex entries
Reach a Renown Level of 5
Reach a Renown Level of 10
Reach a Renown Level of 20
Reach day 1000
Finish the Prologue
Complete the 'Strength in Numbers' campaign mission
Finish the Campaign
Help the Vanguard retake Wealden
Participate in the final battle during a Scourge Crisis and save the city
Unlock and travel to the region of Dragate
Visit every city
Survive the battle to save Andilon during the prologue
Obtain a Named item
Obtain a Legendary item
Obtain 5 Legendary items
Amass 15,000 coin at once
Fully explore a dungeon
Find and interact with every Shrine
Unlock all jobs
Obtain all Journal entries from every region