How to avoid imbalance when introducing a necessary but powerful item with this scenario on inter planer travel. (A followup question) [closed]

Question

In my previous question I asked about the legitimacy of creating an interplanar portal that would return PCs to the wrong place or time. Can I have an interplanar portal return someone to the wrong time or place?

In follow up, I'd like to ask how to avoid imbalance by suddenly introducing a very rare item. Is there a generally agreed upon, yet believable way to introduce necessary items? If so, should I cause some sort of decay in the item so it doesn't break game balance later on.

Here is the situation

My PCs are level 3 or lower. One of their buddies has been unable to join for many sessions. So I had a phase spider carry him off to the ethereal plane. He is returning this week so I want to launch a rescue mission.

The PCs will need the Well of Many Worlds to rescue their friend. I want their attempt to return home to result in either

1. an alternate reality where the location is right but things are very wrong (think Back to the Future 2)
2. or they are returned to a very distant land and every attempt to return home results in something different.

To get home they have to solve the puzzle of what caused the "glitch".

The only way I can think to introduce the Well of Many Worlds is via loot from killing a monster but that feels too hokey. What is a level appropriate means by which the players can access that item?

Once they have it, should I introduce decay to this item so the PCs don't carry it forever?

Bottom Line on the Item:

1. I'm concerned about the consequences of introducing this powerful of an item so early.
2. And I'm unsure of how to go about getting this item into their hands.

A good answer will show a level appropriate way to introduce the item without it unbalancing the adventure tier the players are currently operating in.

UPDATE: I introduced the Well of Many Worlds tonight. An NPC pulled out a black handkerchief and blew his nose on it. It had all the appearances of a silk 'kerchief. He didn't like Orcs. So he cast it on the Orc Paladin feet. The NPC disappeared before the Orc could take action. A bit later the phase spider which has been haunting our Pcs returned and cause the handkerchief to make a faint crystal chime sound. When the Orc picked it up, the slime caused it to fall to the ground and the portal was created. ... And that's how I introduced a very rare necessary item. The phase spider's presence unlocked the power of the once disguised handkerchief. Will add another update when I figure out the limits of Well of Many Worlds to avoid imbalance. Any ideas?

Answer 1

One of the biggest questions is how many times do you expect the players to use the device while they figure out the "glitch"? Next would be, what are the consequences of NEVER fixing the glitch?

As for limits, there are a few umbrella ways to put a limit on a device (and by device I mean whatever mechanism you're considering):

• time
• resources
• usefulness

Time

The problem with time as a limitation is that it truly has a finite lifetime and cannot be used as a future plot device. Unless that's part of some time loop/paradox thing you want to cook up. Also, unless there is a countdown clock available to the PCs they may not understand there is a time limit.

• The characters only have 48 consecutive hours to solve the "glitch" before the device burns itself out.
• In 3 days, the original owner will find the PCs and take the device back, even if they haven't solved anything leaving them stranded.
• Each use of the device requires more and more time between uses. In the beginning it may be hours. Later is takes days to recharge. Eventually you could have it only work on certain full moons.

Resources

This is more easy to meter out and can have farther reaching effects.

• There are 5 gems on the device, and each use breaks/burns out one of the gems. Once the gems are gone, no more uses. However you can make sub-quests to find/create more gems.
• The device runs on life force. The first use drains 1hp from the users (1 per everyone transported). The next use costs 2hp. Eventually the hp cost will become too high until the characters are higher level and can better explore the cosmos. Eventually the sacrifice may be a 24hr drop in CON per use. Full rest to get back.

Usefulness

This is more difficult to quantify, but the possibilities still exist. It also depends on the nature of the "glitch".

• There are only a few set places that the device can transport the players to, but based on the nature of the "glitch" they appear different. Once the "glitch" is fixed, the player see that they just keep repeating the same five places with little point in revisiting.
• There is a "home" state to the device. Meaning that once the "glitch" is fixed, you can transport all over, but after an hour, you always return home. So the players can explore, but they only have one hour to resolve everything before going "home". And home does not have to be a friendly place; it could be the Ethereal plane which means they need to escape all over again.
• The device was designed to explore. It was only because of the "glitch" that players were able to revisit the same place. The true nature prevents the device from returning to the same place (realm, land mass, area, plane of existence, etc) for a year. Sure you can travel the world, but it could be a year before you see home (or a human) again.

Hopefully these give you some ideas (feel free to mix and match a few). But without a better understanding of the device and the "glitch" this is all just concept work.