Toad King Card card_brackish_mangrove

What it is for

Card: fits into Right hand gear that has a free slot.

Chance to cast a Water strike on attack 6%. Damage against bosses +22%.

Weighs 2 of your carry capacity — and weight is what stops drops once the bag fills up.

The best source is Toad King, at 0.020% per kill. You can farm it at Brackish Mangrove.