Cloudy Conjuration( Complete Mage, p. 40)
Your conjured creations and summoned beings appear in a puff of sickening black smoke, and you vanish in a cloud of the same when you teleport.
Spell Focus (conjuration) or conjurer level 1st,
When you cast a conjuration spell, you can choose to have a 5-foot-radius cloud of sickening smoke manifest. The cloud can appear in your space, adjacent to you, or in the space of or adjacent to your target (if any). The cloud lasts for 1 round. Any living creature is sickened while inside it (but not after exiting). The cloud in all other ways acts like a small area of the fog cloud spell. Creatures immune to poison are immune to the sickening effect. The cloud appears in conjunction with the spell taking effect (not before or after). Any creature you call or summon with the spell is immune to the sickening effect of the cloud.
A conjurer can select this feat as a wizard bonus feat.