After getting into it with people on forums, blogs and comment sections I come over here to refresh myself. D&D is good. I am content.
The SCP Wiki is a great source for gaming ideas. Despite its high-tech feel, many of the entries are perfectly adaptable to fantasy games. Here are two for you all:
An old rusty nail. When hammered into the ground in someone's shadow, it restricts their shadow's movement. They can only move as far as their shadow is still under the nail at some point. The victim can't pull up the nail, but anyone else can. If the light source is moved, the victim is pulled by an invisible force so their shadow remains under the nail. This can cause harm if the light source is moved fast enough (up to the equivalent to falling damage).
VASE of INTERDIMENSIONAL COMMERCE
A red ceramic vase that contains a conduit to the Plane of Air. When the vase is touched, it summons an air elemental who represents Yan-C-Bin
, the prince of Evil Elemental Air (or maybe a Djinn emir, or whatever you want). This elemental can speak and greets the user immediately, asking what they have to trade.
The elemental usually assumes that whatever the user is holding in their hand at the time is for trade, but will wait 1d4 rounds for an item if the user isn't carrying one or changes their mind. This whole time it will voice complaints like "I came to trade! What do you have?" or "My patience wears thin, solid entity!"
If no item for trade is produced after the waiting period, the elemental will strike the offender by surprise (12 HD air elemental, 2d8 damage, or by your system) and then return into the vase until summoned again. If may also attack if pestered repeatedly with bogus or uninteresting trades, but only ever attacks for one round before leaving.
Once an item is offered, the elemental will:
a) decline the trade peacefully if it doesn't want the item or already has one, sometimes with a cryptic comment or hint, then depart.
b) accept the trade. The elemental will depart back into the vase with the item, returning in another 1d4 rounds with an item of similar value which is somehow related (in the elemental's mind at least).
For especially rare, expensive, dangerous or anomalous items, the elemental may pause to consider the trade for some time - usually emitting a low humming for the duration.
How Trades Work
This will require a lot of quick thinking on the DM's part. There are plenty of examples in the link.
Items that shouldn't actually be able to fit through the vase opening can still be traded both ways. It's a planar gateway.
Maybe you offer it a plain longsword, and you get back a random weapon, or a few steel ingots? As long as the DM is consistent with the way the elemental thinks, the players can learn how trading works and try to get something cool.
Trading magic items would be fun. Maybe you give it your flametongue
sword and it gives you back a ring of fire resistance
or another fire-related item. Or perhaps it goes in the opposite direction and gives you a frost brand
instead. The possibilities are endless!!