Spring-heeled Jack in the Mythos

Another "using weird phenomena in the Mythos" post:


"Spring-heeled Jack" was a phenomenon from Victorian England: mysterious figures capable of superhuman feats of jumping, which terrorized people in London and many other parts of England. Spring-heeled Jack was sometimes described as being able to shoot blue or white fire, having burning eyes, or even having sharp claws. (See the Wikipedia article).

Despite popular legend, "Spring-heeled Jack" is not a single individual. At least four are known to have existed, though there were likely more.

Spring-heeled Jacks are named for their amazing leaping abilities. This ability is actually merely a part of their greatly increased agility. The other strange ability they are known for is producing blue-white flame; this is an electrical phenomenon similar to "St. Elmo's fire".

A Spring-heeled Jack is produced by exposing a human being to carefully modulated electrical pulses at a certain amplitude and frequency. If this is done correctly, the person's muscles are supercharged and a "Spring-heeled Jack" is produced. The technique was developed in 1836 by the English doctor Isaac Baker Brown, drawing on experiments by the Italian scientist Luigi Galvani. After three experiments recorded in his book "On Diseases and Conditions of the Muscular System, and their Treatments" (and possibly more unrecorded) he gave up the practice. The only known Spring-heeled Jack that did not result from Brown's experiments was accidentally produced in the small American town of Los Amigos by early experiments in the electric chair. That creature seemed to be more powerful than the normal Spring-heeled Jack, resisting bullets.

(If you're not interested in the RPG side of the Mythos, then ignore the following:)

In game terms: A Spring-heeled Jack's DEX increases by 2, but POW (in d20, Cha) decreases by 2. The St. Elmo's fire ability is harmless, but casts light as if a lantern.

A Spring-heeled Jack lives in this state for one week to three months after transformation. After this, it has a 50% chance of dying of heart attack; if not, it loses its increased DEX and 2 INT, but can live for as much as triple its previously natural lifespan.


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The Los Amigos reference derives from Arthur Conan Doyle's "The Los Amigos Fiasco".