I had Drannith Magistrate in play "Your opponents can't cast spells from anywhere other than their hands."
My opponent had Lurrus of the Dream-Den in play "During each of your turns, you may cast one permanent spell with converted mana cost 2 or less from your graveyard."

It seems to me that Drannith Magistrate would block the Lurrus of the Dream-Den ability, but my opponent was able to cast permanent cards (which, in my understanding, are spells until they enter the battlefield) from the graveyard. This interaction doesn't make sense to me.