Miner's Ring, A System-Agnostic Magic Item

Dwarven Miner's Ring

Description:  A simple brass finger ring inscribed with a stylized image of a perching canary in a cage.  Magical sense detect only a faint protective aura.

Powers:  The wearer of this ring is receives a +4 bonus to resist the negative effects of inhaling smoke, gas, particulates, or any airborne poison, magical or natural, and is immediately alerted when entering an area of bad air by the ring's frantic chirping.  They also consume half as much fresh air as they would otherwise.

Possible Origins:  These rings are most commonly created by Dwarven artisans as coming-of-age gifts to younger relatives going to work in the deep mines.  They are fairly simple to make and produced with relatively inexpensive materials, and many Dwarven families have at least one such ring as a family heirloom passed along from one generation to the next.  Some few have been sold to outsiders, usually to other miners or adventurous delvers, although this practice is frowned upon by traditionalists.     

Complications:  The ring must be "fed" and "watered" with a handful of birdseed and a small cup of water each day or it ceases to function until it receives its due.  Fancier versions of these rings come with a small pouch containing a handful of tiny brass seeds and a tiny brass watering cup, which will indefinitely fulfill the ring's needs if it is placed in the pouch for an hour each day. 

Design Commentary:  A minor magic item, the type many wizards would sneer at.  The Dwarves themselves would insist their making is the result of skill and wisdom, not spellcraft.  They can certainly be a lifesaver down in the mines, and they'd probably be really popular with starfarers using the old Spelljammer rules if they learned of them.  Perhaps there's an adventure to be had with escorting a very foreign merchant to the Dwarven realms to negotiate a purchase of a job lot of rings for resale among the stars?