Anti-Magic Rune Stone

This small rock measures 3 inches in diameter and weighs 2 ounces. It bears a mysterious sigil. Typically, 1d4 stones are found together.

You can use an action to throw the stone up to 60 feet. The stone explodes on impact and is destroyed. The Antimagic Field spell is automatically cast for a 20-foot radius of where the stone landed. Each creature within the sphere is unable to cast magic or use any magical items for 1 minute. A sphere of blue light then highlights the area for 1 minute. After 1 minute the effect wears off and the area returns as normal. 

Notes: Damage: Force, Damage, Control, Combat, Consumable