Mass Suffocation

The material below is Open Game Content from the 3PP Source

Suffocation, Mass
School necromancy; Level sorcerer/wizard 9, witch 9
Target one living creature/2 levels (no two of which may be more than 30 feet apart)
Duration 1 round/level

This spell functions as suffocation except as noted above. Note that the duration of this spell is much longer, forcing those suffering from the effect to make far more Fortitude saves to stave off eventual suffocation.