Does it need to be 4e, or are you willing to convert something?
Well, the Keeper is the deity of death, so... what if you had a makeshift Charon like in Greek mythology since you're looking for a ship-based thing? Someone who could act as a ferryman? There's a mysterious ship in Eberron lore from The Explorer's Handbook that might work called The Crimson Ship, piloted by a mysterious Ultroloth (Neutral alignment, or Unaligned in 4e, I'd guess) who's known only as The Captain. Basically, when a person is desperate for a ride, when there's blood in the water, and there's a furious storm, some say the Crimson Ship arrives.
The Captain offers a passage, but only in exchange for a task on the way, most often combat. I know that levels and CRs don't exactly match between 3.5 and 4e, but the Level 12 encounter suggested is something called "Sailing the Sea of Fire." Basically, the ship carries you to the volcanic Lake of Fire in the Demon Wastes. The Crimson Ship sails through the lava, and catches up to a longboat with a Rakshasa and two Zakya Rakshasas in it, and The Captain requires anyone sailing in this challenge to bring back the heads of all three. The longship has a pretty hefty treasure in it (listed as a Double Standard CR 10 treasure, though I'm not sure how it'd translate to 4e) and that the Rakshasas will definitely use any useful treasure items (potions, armors, magic weapons, etc.) that they have available.
Considering you'll be in the Demon Wastes *anyway*, The Captain might be a good "Charon" figure, and this challenge might be suitable (I don't know if 4e ever used the Zakya Rakshasas, but I think something could be quickly reflavored to fit the mold.) I'd recommend finding a cleric or priest of The Keeper, and saying that the Lair of the Keeper is geographically constant, but you must make the metaphysical journey to reach it. and make it "really" be the Lair of the Keeper, and that this priest does something to arrange for The Captain to arrive and offer the journey.
Oh, and for the record; in addition to apparently being lava proof, The Crimson Ship is one of the rare Eberrons ships that can sail in water *or* fly through the air, without needing a Khyber shard to propel it.
For the record: the journey on The Crimson Ship usually takes a few days (even if the destination is near), and The Captain stays mostly to himself, but makes a point of visiting each passenger once per day to inquire about their lives and how they're faring on the trip. Whenever his passengers finish a task, he thanks them, walks to the State Room, goes to a Conquer board, and moves a single piece on it. He never answers any questions about that Conquer game, and if challenged to play a game he produces a second board. He's *very* good at Conquer, though. (I don't know if 4e talked much about Conquer, but it's basically a strategy game like chess.)
So... would this work for you?
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Totally open to convert something.
Beoric wrote:
That sounds fantastic! I appreciate the input! I'll definitely follow up on that.
Afgncaap5 wrote:
hobson1975 wrote: