You can befriend a bee (it will follow you around and even go between floors with you) if you throw an elixir of honeyed healing.
I thing Yog-Dzewa is an otherworldly demon that got the Yendor amulet and it uses it to grow in power with it. As the dwarf king says, it's power over this world is limited. Maybe it wants the amulet to conquer this dimension; is what I thing an otherworldly god that has limited power but can gain more with the amulet would try to do. Also, the dwarf king's mission as of right now is to stop Yog-Dzewa's minions from arising.
And it's not like the king wants the amulet for just that, keeping Yog-Dzewa at bay, he uses it to controll the minds of the whole city.
Probably they sent you down there to stop the dark magic from below, aka return the amulet of Yendor to the surface, as if not, its dark magic would probably start leaking onto the surface, and that'd be bad.
I think that the amulet isn't the one that's resisting to be freed, I think it's Yog controlling the amulet the one that empowers the enemies and beckons them to you.
But that's just my theory...