Bow of the Spelldrinker

Alter: This gilded bow creates hazy illusions of the cosmos when drawn. Attacks made with this magic bow deal an extra 1d4 force damage to any target hit by it.

When you see a creature casting a spell within 60 feet of you while holding this bow, you can use your reaction to draw from your own life force and attempt to counter it. When you do, you can take 30 force damage, which can't be reduced or prevented in any way, and fore a magical arrow of pure force from the bow toward the creature. If the creature is casting a spell of 5th level or lower, its spell fails and has no effect. In addition, the target must make a DC 16 saving throw, using its spellcasting ability. On a failed save, the creature takes 30 force damage as the magic is ripped from it. On a successful save, the creature takes half as much force damage. Once this property has been used, it can't be used again until you finish a short or long rest. 

Attunement: Yes
Rarity: Very Rare
Type: Bow
Cost: 37350gp

Griffon's Saddlebag Vol II