Momir Vig, the Simic guildmaster, wished to fulfill his guild's ancient purpose - to preserve the health of all Ravnican life-forms. Of course, he was not exactly satisfied with such a mundane goal, so he expanded it out to improving the biological construction of all Ravnican beings. Under his influence, the guild shifted from fighting to preserve the essence of Ravnican life forms to working to improve them, regardless of whether the subjects particularly wanted to be improved.
Vig and his Simic followers do want to make your life better, but they do not feel they need your permission to do so, and they're not asking how you'd like to have it improved. Most self-respecting Ravnicans are not exactly comfortable with this sort of doctor/patient relationship. Most of Ravnica's sentient beings are caught up in the hustle and bustle of city life. There's no time for hanging out in a pod-chamber at Novijen, waiting for a sporomantic cell to split and grow you a second pancreas. This is not to say that the Simic do not perform the regular duties of physician or researcher. The injured and infirm often visit the offices of reputable Simic doctors. But for those who are not currently experiencing the trauma of Clinging Darkness or burns from a run-in with a Pyromatics display, the Simic are viewed as quacks and mutant-makers. So, except for the mindless Ursapines of the world and the brown-nosed Simic initiates, nobody has time for the Simic and their crazy operations.
So what was a megalomaniac to do? Nobody understood that he was only out to “improve” lives. Well, if the people would not come to be improved, the improvements could be brought to the people. This was the driving thought behind the creation of Momir Vig's greatest discovery, Cytoplasty.
Cytoplasts are a wondrous bio-magical invention. They are small masses of living magical tissue, usually translucent gelatinous blue-green blobules, that convey genetic information to and from whatever life-form they come in contact with. A cytoplast from an intelligent host can be transferred to the head of a doofus - then the bluish blob will begin to incorporate itself into the genetic makeup of the dimwit, increasing his intelligence in the process. After long periods of cytoplastic connection, the jelly-like bluish cells will also assimilate cellular information from the new host and take on its own characteristics. For example, if the aforementioned doofus were a snake man, the cytoplast would transfer intelligence to the serpentine brain, then absorb biological information from the host and take on a scaly appearance. Genius!
Still, this new technology required a somewhat willing recipient. Cytoplasts still had to be grafted on to a submissive host. It was a painstaking process involving scalpels, mana, and a skilled Simic surgeon. Even after cytoplasty led to many successful biological improvements, the people still were not all that jazzed about having living jelly lumps attached to their bodies - even if it meant a higher IQ or a faster time in the Gnat Alley Marathon. Momir Vig was frustrated by this hindrance to a grand scale overhaul of Ravnican genetics. To him, the people just lacked vision. If they could be made to see it, all would fall into place. So he went back to the scrying vats and cooked up a new improved scheme. This one involved more magic and more mana, but no cutting and, most importantly, no cooperation from the host-patient! He had developed a form of cytoplast that could be cast from a host like a small gelatinous projectile, immediately incorporating itself into the genetics of whatever living thing onto which it happens to splat. The genetic infusion process was almost instantaneous, though the assimilation of host genetics was still slow. But that was less important. At last, Vig had created a method of spreading genetic improvements without consent. In his mind, the consent would surely come once the people grew attached to their new strengths and abilities.
"I must speak with Momir Vig about creating a water-spouting watchdog." -Mathvan, Prahv scrollwarden (Hellhole Rats)
"Show them to Razia and then to the Azorius sky marshals. We could create a fine bidding war -enough to fund the final stages of Project Kraj." -Momir Vig (Assault Zeppelid)
"The unnatural pressures of life in this city are best withstood by lifeforms that adapt with unnatural swiftness." -Momir Vig (Novijen, Heart of Progress)
"Of course it will grow beyond control -it was designed to choose its own evolution." -Momir Vig (Experiment Kraj)
"Look beyond, to the vascular awareness that all life is a map to greater knowledge." -Momir Vig, Biomancy, vol. I (Biomantic Mastery)
"We've bred out the shortcomings of the species' natural form and replaced them with assets of our own design." -Momir Vig (Simic Sky Swallower)