The Warlock Well sits in the town of Goldvale but has existed in one of my past campaigns. The premise is simple: Players toss in magical items of whatever sort and an entity grants them perks or powers based on how potent what they toss in is or what its agenda is. This a role playing goldmine because it allows non warlock characters to create a semi-warlock like link to the well, which could turn into more. Sadly this hasn't seen much use in my games yet, but if a PC ever throws in a powerful magical item they'll likely find themself gaining some power related to it, or some perk from an entity in another dimension which may come back to bite them in the butt later. There are very few safe deals for power in a fantasy setting. But that keeps it interesting.

A little fine print for the Warlock Well as it gets used or sucked into plot lines…

• The name “Warlock Well” doesn't imply true warlocks in so much as it implies the sort of wheeling and dealing over abilities granted. This could mean real bargains are struck between entities just like warlocks, it could means a warlock origin story or multi-class character twist could begin here, or it could be the pathway toward strange favors and deals with anything from demons to gods.
• Nothing thus far says transactions made through the Warlock Well must be evil in nature. Think of it more as a conduit, the sketchy communication system with the mystical, mythological, or just clued in things that exist out there. This could imply on the same plane of existence or others.
• Sam Smith the dwarven bandit threw the Handy Haversack “artifact” into the well.
• Cole's long vanished mother used the well when he was very little. To what end no one knows.
• Jim Bob The Bullfrog spent some quality time here & considers it home whenever possible.
• Matilda went all in with the Shovel Of Alden and Kelthor's Book of Great Awareness here.
• Alimir solidified his bond to his god here & used it to get his memories back.
• Apparently some things that happen here can even survive timelines branching, as per the Nephele Timeline Branch Event.
• Mustard Mike was notably the first NPC that The Party was aware of and knows personally using the Warlock Well. He traded in a jar of endless mustard for the ability to dispense mustard magically out of his finger. While this sounds innocent enough for a Dragonborn that has taken on the roles of mustard salesperson & pirate, the fine print of whatever deal was reached via the well is unknown at this time. This transaction was somehow related to Mustardia.