What Is Bean's "Destiny"?
For most of Disenchantment season 1, Bean is presented as an incredibly ordinary person (royal lineage aside). However, the finale seeds some major doubt in that. First, sparking her own suspicions, when reaching for the seeing orb it sparks with black electricity. Subsequently, her mother starts a non-sex talk with Bean (that the show cuts away from), and then Dagmar says to Zog she's involved in "a dark battle of a hundred centuries and our daughter's destiny."
It's all very vague, with suggestions of dark magic and massive plots similar to Game of Thrones' Azor Ahai or countless other fantasy prophecies. What we're almost certainly dealing with, in that vein, is something bigger than any one kingdom, although there are scant clues to what. It doesn't seem as though Dagmar tells Bean anything of much importance: the Queen still tries to frame Oona even after the "talk", and Bean's still highly inquisitive on the boat.
Who Attacks Luci?
Near the end of Disenchantment season 1's finale, Luci is wandering around the castle complaining that he's not the one causing destruction, only to be attacked by an off-screen assailant. Luci definitely knows who it is, gasping and saying "you" before a sucking sound is heard, likely him being stuck in a jar.
That jar sound suggests it's Big Joe, the necromancer who already tried to kill Luci once on King Zog's orders and was last seen trapped under a desert of sand in The Lost City of Cremorrah. Considering he escaped certain death once before with just a dismemberment, a return isn't surprising, and the demon would definitely be a target.
There are some other potential captors, however. Oona is currently still in Dreamland sliding around the castle, and Prince Derek was sent up into the tower, so either one could have nabbed him.
Who Is Dagmar Working With?
After freezing all of Dreamland, Dagmar takes her daughter to a nearby ship manned by various creatures. They greet the Queen and Princess by name, freak Bean out by staring at her, and then the ship sets sail "for the homeland and a glorious future". Evidently, Dagmar doesn't act alone.
But who are they? The humans on the boat appear to be of Asian ethnicity, so it would be a safe guess this is a land from across the sea from Dreamland, possibly on the same continent as Maru and Cremorrah. It may even be the former, who have already displayed an interest in destroying Dreamland: Luci's real purpose could have been to emotionally challenge Bean so she would, in her confusion, save her mother over Elfo, thus restarting the hundred-century war.
Whoever is behind it, the promise from Disenchantment's ending is that the show will be very different in season 2 (although it wouldn't be surprising if all of these plot threads are resolved in the premiere before resetting to a standard status quo).
Who Saves Elfo In The End-Credits Scene?
Disenchantment may be on Netflix, where the end credits are pushed to one corner for advertising more shows, yet it surprisingly has a short stinger. This shows Elfo found by two unseen figures and dragged from the sea. Elfo died from an arrow wound in the previous episode and was knocked out of his coffin over Dreamland's falls by the Queen fight, but this provides the first concrete clue (beyond him being a main character) that he'll be resurrected somehow.
But by who? The scene actually reveals it - one of the people dragging Elfo away has long, red hair, a bracelet... and scales. She would appear to be a mermaid, meaning Disenchantment is finally going to visit Mermaid Island after a near-miss in episode 2. How they can bring Elfo back to life depends entirely on how they're characterized.