Horn of Fog

Wondrous item, rare

This item has 7 charges. It regains 1d6+1 charges every day at dawn. If you expend the last charge, roll a d20. On a result of 1, the horn explodes, dealing 3d8 cold damage to all within a 20 ft. radius sphere. This horn resembles a small bugle. When blown it emits a deep, foghorn-like sound. Expending a single charge allows the caster to cast fog cloud. Each additional charge expended increases the effective spell slot by 1.