Here is the full list of all 30 Avadon: The Black Fortress achievements.
Get your main character to level 10.
Get your main character to level 20.
Get your main character to level 30.
Show that Holklandans and the Kellem can work together.
Eliminate the threat to the Kva.
Bring all four of your allies back to Avadon.
Complete Avadon: The Black Fortress on Normal difficulty or higher.
Prove your loyalty to Redbeard.
Showed the ogres just how foolish they were.
Hunted down the Shadow Beast.
Purged a tower of its unspeakable experiments.
Cleansed the Beraza Woods of bandits.
In the Farlands, no foe of the Pact can be left standing.
Locate the crypt of the Keepers.
Augment 50 items.
Fight your way back into the castle.
Meet Redbeard.
Calm the dragon Zhethron. For the first time.
Found a secret door.
Augment ten items.
Hunt down the greatest prey. (Normal difficulty or higher.)
Send Beloch the Scourge back where it came from. (Hard difficulty or higher.)
Complete Avadon: The Black Fortress on Hard difficulty or higher.
Complete Avadon: The Black Fortress on Torment difficulty.
Claim Avadon for your own. (Normal difficulty or higher.)
Reach the endgame without ever using a Resurrection scroll. (Normal difficulty or higher.)
Reach the endgame without ever making one of your companions happy. (Normal difficulty or higher.)
Reach Castle Vebeaux without one of your characters ever going unconscious. (Hard difficulty or higher.)
Find all codex entries.
Reach the endgame and never have more than one character beside yourself in your party. (Normal difficulty or higher.)