Corruption

Corruption is a 3-Energy Ironclad rare Power (2 upgraded) that makes all Skills cost 0 Energy but Exhaust when played. This single card transforms the Ironclad's toolkit: every Block card, every exhaust trigger, every utility skill becomes free for the rest of that fight. Combined with Feel No Pain, Corruption creates a self-sustaining engine where free skills generate Block while exhausting. Combined with Dark Embrace, every free skill draws you a card.

Corruption enables some of the most powerful turns in the game: play every skill in your hand for free while generating Block from Feel No Pain and drawing from Dark Embrace. The Exhaust ensures skills don't cycle back, which is mostly fine since Corruption turns each one into immediate value. The 3-Energy cost means you sacrifice your turn to play it, but subsequent turns are often unstoppable. A build-defining rare.