-- Robert E. Howard, Hour of the Dragon
Xaltotun's Smoking Doom
Duration: 1 round / level
The caster tosses a handful of dust on the floor near the intended victim which will immediately begin to coalesce into a serpent of semi-solid smoke. This coalescence will take 1d3 rounds. Once complete, if the victim is still in range they must make an immediate savings throw versus death. If they succeed, they have managed to avoid the serpent's grasp this round. Failure indicates that the victim will perish in a number of rounds equal to their HD or level (will only affect creatures up to 8 HD). During strangulation the victim may neither speak or act, capable only of flailing wildly.
The serpent of smoke will continue to strike every round for the period of its duration, at which time it dissipates. If the victim moves out of range, the serpent will coil in wait, striking again at the first opportunity. The serpent cannot be attacked except by magical means. It has an AC of 9 and an equal number of hit points to its caster.