Miasma(Masters of the Wild: A Guidebook to Barbarians, Druids, and Rangers)
Level: Druid 4,
Components: V, S, DF,
Casting Time: 1 action
Range: Medium (100 ft. + 10 ft./level)
Target: One living creature
Duration: 5 rounds/level
Saving Throw: See text
Spell Resistance: Yes
By filling the subject's mouth and throat with unbreathable gas, you prevent him or her from doing much more than coughing and spitting.
The subject can hold his or her breath for 2 rounds per point of Constitution but must make a Constitution check (DC 10 +1 per previous success) each round thereafter to continue doing so.
Failure on any such check (or voluntary resumption of breathing) causes the subject to fall unconscious (0 hp).
On the next round, the subject drops to -1 hit points and is dying; on the third round, he or she suffocates (see Suffocation in Chapter 3 of the DUNGEON MASTER'S Guide).