Kraken Clutch Ring

This green copper ring is etched with the image of a kraken with splayed tentacles. The ring has 5 charges, and it regains 1d4 + 1 expended charges daily at dawn, as long as it was immersed in water for at least 1 hour since the previous dawn. If the ring has at least 1 charge, you have advantage on grapple checks. While wearing this ring, you can expend 1 or more of its charges to cast one of the following spells from it, using spell save DC 15: black tentacles (2 charges), call lightning (1 charge), or control weather (4 charges).