Ectoplalm
This stuff replaces regular napalm for the flamethrower (use the stats for the weapon found on page 37 of The Day After Ragnarok). It does considerably less damage (2d6) to normal targets, but it is pure death on Serpent-Tainted objects and monsters (3d10). Bizarrely, Ectoplalm acts as an extinguishing agent on ophiline (refined Serpent oil). If used on the countryside, a full tank of Ectoplalm can reduce the Serpent Taint of a quarter acre of land by 1. This is of course done by burning everything down to the grassroots, but it works.