Rod of Icicles

This white crystalline rod is shaped like an icicle. The rod has 5 charges and regains 1d4 + 1 expended charges daily at dawn. While holding the rod, you can use an action to expend 1 of its charges to attack one creature you can see within 60 feet of you. The rod launches an icicle at the target and makes its attack roll with a +7 bonus. On a hit, the target takes 2d6 piercing damage and 2d6 cold damage. On a critical hit, the target is also paralyzed until the end of its next turn as it momentarily freezes. If you take fire damage while holding this rod, you become immune to fire damage for 1 minute, and the rod loses 2 charges. If the rod has only 1 charge remaining when you take fire damage, you become immune to fire damage, as normal, but the rod melts into a puddle of water and is destroyed.