Here is the full list of all 13 NECROPOLIS achievements worth 1,000 gamerscore.
Has been slain by a diabolical contraption.
Has consumed something without even knowing what it is.
Has survived longer than your average dungeon delver.
Has found some fancy new duds.
Recovered your first Codex.
Has slain an enemy using a power attack.
Has crafted something (mostly) useful.
Has been slain in the Necropolis.
Traverse down a Level without using an elevator.
Recover all Codexes.
Escape the Necropolis.
Obtain fifteen thousand gems.
Learn to craft everything.