Bulwark: The Forbidding Fortress

From publisher description:

Heroic Co-operative Deck-Building!

This recently-repopulated fortress in the deepest bowels of dwarf territory has formidable defences - but facing equally formidable armies are the stock-in-trade of heroes in Bulwark! With guards, secret tunnels and levers that pour hot lava into the ranks of the enemy, there are are lot of tools at your disposal. Its most valuable assets - the sequence of gates guarding the main causeway - would become its downfall should they be breached.