Appearance Additional Content, Collection Achievement

[thorny pewter]

I've one missing item on appearance on additional content category,

Will it affect the collect all collection achievement?

[digital plume]

DLC will not affect the achievement, no, however empty spaces will not appear for DLC you do not own; what you're missing is probably the mask earned by completing the Dark Arts Arena.

[thorny pewter]

ohh ok,
I'll look into it..

Thanks