Spikes were two-pronged impaling devices with a single-hand handle developed by the Indian Brotherhood of Assassins. When used to pin a target to the ground, the spike itself would emit a substance that was known to provoke terrifying hallucinations, causing the target's fear to spread to enemies around them. The target was likely to scream in fear and pain, both causing panic among those who witnessed the impalement and drawing the attention of additional opposition from further away.
Following the marriage of the British Assassin Evie Frye to Jayadeep Mir, an Indian Assassin who had served as a Mentor of the British Brotherhood, Evie's twin brother, Jacob, visited India around 1873, bringing with him an initiate they called "Jack the Lad". There, they learned the fear tactics of the Indian Brotherhood which were subsequently imported back to the British Brotherhood.
When Jack turned rogue and became a serial killer, spikes became a part of his arsenal, employed during the "Autumn of Terror" he inaugurated over London in 1888. That year, when Evie returned from India to stop Jack's spree of murders, she too utilized spikes throughout her mission. However, whereas Evie used the spikes in a non-lethal manner, Jack had no such qualms.
By 1916, however, the use of spikes by the British Assassins had been apparently discontinued.