A knight errant might manage to kill a ghoul and a peasant with a pack of dogs can at times take down a bear. Yet let us make one thing clear: not even the finest steel armor ever forged or the collar bone of Saint Plegmund himself will give a mortal man any chance of surviving a fight against the creatures that dwell deep beneath the earth. – veteran Toussaint Ducal Guardsman, briefing new recruits
Imagine a creature that kills men, feeds on kikimore eggs and digs underground tunnels so wide they'd fit the emperor of Nilfgaard's coronation carriage along with a team of six horses. And now imagine this creature digs with such force, the earth quakes and the houses up above tremble and collapse. Noting these symptoms, Geralt was at first unsure what sort of a beast he could be dealing with, knowing only that he needed to be very, very careful.
Only after he carefully examined the monster's tracks did he realize it had to be an aged female shaelmaar.
The monster destroying Tufo turned out to be an old shaelmaar matriarch. Geralt hunted it down and fought it deep under the ground.
Though blind like all members of its species, this creature could easily maneuver by sensing vibrations and noises. As long as Geralt stood quiet and motionless, he was safe. Yet if he took one step or breathed a bit too loud, the matriarch would start moving in his direction with great speed.
Geralt had a very difficult time taking out this monster, whose armor could not be pierced by any of his weapons. In the end, however, he succeeded and the monster of Tufo was no more.