A spiked cage can be built in the prison hotspot of the Oubliette in a player-owned house. It requires level 80 Construction to build. When built, the player earns 500 experience. Building spiked cages requires the second highest level of Construction needed for prison building, next to bone cages.
When a trapdoor is activated (and if an Oubliette is below a Throne Room), players standing on the trapdoor will fall into the Oubliette and into the prison. Other types of prisons are oak cages, oak and steel cages, steel cages, and bone cages.