Enchanted Tuning Fork

Enchanted Tuning Fork (Wondrous Item, Very Rare) is the generic name for a magical item meant to facilitate the Plane Shift spell as a ritual by magic practitioners who might otherwise be unable to use the spell.

Description
Each plane has a unique resonance that a tuning fork of specific materials and pitch can match to facilitate a Plane Shift spell to said plane. Most forks are comprised of some kind of metal, and are a handle with two prongs for creating a tone in appearance.

Known Tuning Forks
The Nine Hells (Avernus) - An obsidian fork tuned to G

Ysgard - A nickle fork tuned to G

Mechanics
The caster of the ritual, as well as up to 8 other individuals, gather in a circle for the 10-minute ritual. A sum total of 7 levels-worth of spell slots need to be expended (ie. 1st level spell slot counts as 1, 2nd level spell slot counts as 2, etc.) between all members of the ritual for the spell to be cast. Each tuning fork will only bring the caster and group to its predetermined plane.

History
After the siege on Avernus' Trading Outpost, Tim found tuning forks leading to both Avernus and Ysgard on the body of the Illithid who led the Aberrations.

Following the explosion of the Gluttonous Nupperibo, Tim used the then-unknown tuning fork to Ysgard to pull the Party, as well as Athydin and Wat, out of Avernus and onto further adventures.