Self-Destruct decks use permanents designed to sacrifice or destroy themselves for another effect. The deck treats those cards as disposable tools whose departure is part of their intended value rather than a loss.
Caustic Caterpillar sacrifices itself to remove an artifact or enchantment, while Spore Frog can repeatedly sacrifice itself to prevent combat damage when paired with graveyard recursion. Death-trigger payoffs can make each self-destruction even more profitable.