Corrupted Bone Berry

You summon a corrupted bone berry in your hand. This berry looks like a regular bone berry, a survival check contested by the caster's spell DC will reveal its true nature. It doesn't emit any magic. Once someone puts the berry in their mouth, it expands instantly, forming bony spikes that attempt to pierce the skull of the target. They take 10D6 piercing damage, and are unable to speak until they, or an ally, manages, as an action, to remove the berry with a successful Athletics check contested by your spell save DC. At the beginning of each of their turns, the target takes an additional 2D6 damage until the berry is removed. 

In addition, at any point after summoning the berry and whilst holding it, as an action you can attempt to charm a target and compel them to swallow the corrupted berry. Chose one creature within 30 feet of you, they must succeed on a Wisdom saving throw against your spell save DC, on a failure, on their next turn they will use their movement to get next to you, and if they do, use their action to take and swallow the berry, suffering the effects. If they can't get next to you, the charm ends, and they can continue their turn as they see fit. 

The berry loses it's potency if it has not been consumed within 8 hours of the casting of this spell. Only 1 corrupted bone berry may be summoned and active at any one time.

Bone berries. Normally found in nature, in areas close to swamps, these berries have the appearance and taste of blueberries, but are a bit crunchier, and whiter in appearance hence their name. Osteomancers have tempered with them for nefarious deeds.