20 Running the Gauntlet
Got through Blot Alley by any means
This is a missable achievement
Ian the Ghost asks you to not harm any blotlings as you go through Blot Alley, by ignoring him and destroying them you will get this achievement. This means that you will miss out on a quest and thus miss out on 'Perfectionist'
I got this achievement and Ian the ghost was still there when i returned. However, the side quest ian is related too can still be completed by visiting clarrabell and buying costumes for her. In "One Toon's Trash" you are required to sell things to the museum lady and selling ians costumes will make the quest easier, but this is not required seeing as you can buy back items after the quest is over.