Alright, so near the wraithman spell book in the Soul Cairn there is a tower called The Keepers Lair. And when you go inside there is a platform that you can 'activate'. But it always says that I do not have the correct item to use this. And I've looked on the wiki, YouTube, and this forum. Yet I have found nothing on the topic. So if you guys know anything about this place, or what item i need, I would like to know. Thanks.

are you thinking of the reapers lair, maybe you need 3000 death hound collars

3 reaper gem fragments.

oh that portal, i heard a guy talking about a portal past the reaper so i thought it was that one

Ok it does say Reapers lair. What do I need for it? And where do I get them?

(My TV makes Skyrims text a little sketchy for me to read)

They're in 3 chests, possibly the ones which are under the Ideal Masters.