If a creature is transformed into another creature (say, a human into a dog), then that creature will become more and more accustomed to the new form until a point is reached where reversing the spell is impossible. A second transformation is possible, but the creature will have to go through the whole process again.
An ancient, psuedo-immortal race has been manipulating something important (politics, religion, economics, etc.) for centuries. Hardly anyone is aware of them, let alone their goals.
Five main ingredients were used to create this noxious, real-world (ridiculously named), chemical compound, featuring sulfur as the main ingredient. The odor was said to be akin to rotting refuse, decomposing carcasses, and fecal matter. "Who-Me?" Was developed during WW II by the OSS to aid the French Resistance against the Germans. The idea being to utterly humiliate and ultimately demoralize the enemy by making them stink of garbage left to rot under a hot sun.
The bizarre experiment did not last long however as "Who-Me?" could not be administered on select targets (controlled), without making everyone in a certain radius, friend, foe, and sprayer alike, stink as well