Garkains are lesser vampires, so foul that the mere sight of one paralyses opponents, especially sensitive ones. Apart from using its ugliness as a weapon, the garkain has at its disposal an amazing variety of ways to pin down victims and suck their blood.
"Garkains, the filthiest of vampires, are uglier even than fleders. Since fleders are widely despised for their looks, it is easy to imagine how abominable garkains must be. As vampires, the creatures drink blood but they are also drawn to fresh meat, or even corpses. Garkains are often mistaken for gargoyles because they lurk on rooftops, waiting to dive at their victims."
In Murky Waters, Geralt may have a chat about garkains with a Peasant woman. She is concerned for a family member who suffered a garkain attack and now suffers from poison. Geralt helps her identify the source of the problem. The conversation will result in a Garkain bestiary entry along with any associated ingredient entries he does not have yet.
In Old Vizima at the Hospital(and sometimes in various houses in the area) there is a Diseased man that asks for something to eat. In return, he will unlock Garkains and their alchemies.
Garkains, like fleders, belong to the class of particularly dangerous vampires whose strength exceeds even that of fiends. An encounter with one of their number almost always ends in death, which is why there are not many eye-witness accounts of them. From the city guard reports written up in Lan Exeter describing the attacks committed in that city in 1104 by three garkains (later killed by a certain Olivier of Gulet, witcher), it seems these horrible monsters do not content themselves with drinking the blood of their victims. The investigators concluded from the blood and guts strewn around the crime scenes that garkains tear their victims to shreds with great delight and muck about in their bloody entrails.
Garkains belong to the group of creatures known as lesser vampires. They often gather around themselves members of other subspecies of lesser vampires, acting in such situations as leaders of the pack. They are by and large unable to run, but can jump a great distance and often attack their prey in that way. During combat, they usually keep their distance from their foes, trying to incapacitate them using a blast of mental energy provoking visions that beguile and disorient.
Before grappling a garkain, one should drink the Black Blood potion and stock up on vampire oil. It should also be remembered that the Samum and Moon Dust bombs are always effective weapons against any mental attacks.