Dark Souls Remastered | Starting DLC 3rd step, to Duke's Archives to loot the Broken Pendant

If you've been through Duke's Archives, you may remember a seemingly out-of-place Crystal Golem near the beginning, in the library. After defeating the Golden Crystal Golem (step 2), the next step is to head to the archives and defeat this Crystal Golem, which will drop the Broken Pendant. After this, you will have what you need to enter the DLC.

I suggest first defeating everything around the Crystal Golem before attempting to defeat it.