Rod of Keranos

Rod, very rare (requires attunement by a spellcaster)

Price: 75,000-100,000 gp | high sentimentality

This metal rod is 2 feet long and causes anyone who touches it to receive a harmless static shock.

It hums with energy. With the rod in hand, you have resistance to lightning damage.

Paid

Once a day, with the rod in hand, you can cast the call lightning spell at 9th level.

Overpaid

Once a day for the first ten days after you attune to the rod, you may cast the commune spell without requiring material components to contact Keranos, god of storms.

Source: The Gray Merchant of Asphodel