Goldgrubbers is an epic pirate unit that replaces a non-pirate card in your hand. The strength of Goldgrubbers can be increased by leveling it up. Goldgrubbers sees play in pirate decks mostly.
Goldgrubbers' ability to act as a second replace effect makes it great for cycling your deck or finding combo cards.
Goldgrubbers will replace any card in your hand that isn't a pirate unit. This includes spells and structures, too.
You can also use Goldgrubbers to discard non-pirate cards and draw important pirate cards that might be needed to destroy the enemy base in a dire situation, like First Mutineer and Bluesail Raiders.