This spell generates a billowing cloud of ghastly yellowish green vapors which is so toxic as to slay any creature with fewer than 4+ 1 hit dice, cause creatures with 4 + 1 to 5 + 1 hit dice to save versus poison at -4 on the dice roll, and creatures up to 6 hit dice (inclusive) to save versus poison normally or be slain by the cloud. The cloudkill moves away from the spell caster at 1” per round, rolling along the surface of the ground. A wind will cause it to alter course, but it will not move back towards its caster. A strong wind will break it up in 4 rounds, and a greater wind force prevents the use of the spell. Very thick vegetation will disperse the cloud in two rounds, i.e. moving through such vegetation for 2”. As the vapors are heavier than air, they will sink to the lowest level of the land, even pour down den or sinkhole openings; thus, it is ideal for slaying nests of giant ants, for example.