Should you choose to kill it and draw its blood, be prepared. It changes to a ghoul-ish appearance, and it fights similarly. Watch it closely and be prepared to parry and counter any of its claw swipes.
As you deal damage to it, the Botchling becomes enraged, growing spines similar to those of an Alghoul During this time, the Botchling will begin to regenerate at an alarming rate, and the spikes will harm Geralt should he attempt to strike with swords.
The Botchling is weak to Axii. Use this weakness to pacify the monster, retracting its spines and keeping it in place for you to circle around it to deliver punishing sword strikes. This also cuts off rapid regeneration.
In the Witcher 3: Wild Hunt, Geralt encounters a Botchling while speaking with the Bloody Baron. If Geralt decides to have the baron embrace the disfigured child, the Botchling will become pacified, but if Geralt decides he wishes to take a different route and use the Botchlings blood the Botchling will take on a more hideous and ferocious form.