The Coin of Volin
"This gold coin looks like any other, except one side is brandished with the face of Volin. "
Ibeos
The Coin of Volin
Wondrous Item
Legendary Illusion Requires Attunement
Dormant State: While Attuned you gain expertise in Deception.
Once per quarter you may flip the coin.
If it lands on Volin, you may target one creature and cast modify memory. If you do you may choose to modify it up to 24 hours, compared to the 10-minute duration of the original spell.
If it lands on the sun, for the rest of the quarter, as an action once per day, you may freely cast hallucinatory terrain, in a 150 cubic range centered on yourself. It lasts for ten minutes and is regained per long rest.