Putrid Summons

When you cast a summon monster or summon nature's ally spell, you can choose to summon a single creature that exudes a putrid odor or befouls the water surrounding it, granting it the stench universal monster ability. The duration of the sickened condition created by this stench is a number of rounds equal to the spell's level. When performing a putrid summon, you summon a creature from the next lower list than the spell you are casting. For instance, if you cast summon monster IV, you summon a creature from the summon monster III list.

Prerequisites

Ability to cast summon monster or summon nature's ally