The phrase "damage sponges" refers to things or people that absorb or take a lot of damage. They are often used as a shield or protection against harm for others. Full definition
Some of them are your standard damage sponge enemy with a weird name, where as others require teamwork to overcome. (justpushstart.com)
Bosses also feel like damage sponges at times, where it's less about skill an execution and instead waiting it out until the game stops from auto - blocking you and giving you a few - second window of time to wallop on them. (gamingunion.net)
Damaged sponge tissue is susceptible to disease, which can eventually kill the sponge. (ambergrisCaye.com)