>>125319529>blocks your path
As others have laid out there's basically 2 major mysteries left
1.)Everything regarding Belos, his backstory, and what the Day of Unity is supposed to be. Hunter and the Wittenbane brothers most likely tie into this.
2.) The 'ancient history' mystery. King, his relative, and the Jean-Luc island come into play here. We also had that brief scene with The Collector.