What the achievement asks
Kill all eight bosses of Liberation of Undermine on any difficulty. Ten points, account-wide, both factions.
At current levels this is a queue rather than a fight. Nothing here needs a group you have to assemble, gear you have to earn first, or a difficulty above the lowest.
The eight bosses, in order
| Order | Boss |
|---|---|
| 1 | Vexie and the Geargrinders |
| 2 | Cauldron of Carnage |
| 3 | Rik Reverb |
| 4 | Stix Bunkjunker |
| 5 | Sprocketmonger Lockenstock |
| 6 | The One-Armed Bandit |
| 7 | Mug'Zee, Heads of Security |
| 8 | Chrome King Gallywix |
Queue the right wing
Raid Finder splits the raid into wings, each with its own queue and its own bosses. You cannot reach Chrome King Gallywix by running the first wing, however many times you do it.
Check which wing you are entering against the table above before you queue, and work down the list rather than taking whatever comes up first. That single habit is the difference between three evenings and one.
Check your criteria before you queue
Progress is account-wide, so bosses killed on any of your characters count towards the same total. If you raided this while the patch was current on a character you no longer play, open the criteria list first: you may need one wing rather than four.
Any difficulty counts, so Raid Finder is enough. If a criterion stays grey after a clean run, a Normal clear has always been the reliable fallback for this family of achievements.
Where it fits
A piece of Worldsoul-Searching, the War Within meta. This raid ends the Undermine story, with Gallywix at the end.