The four teams build a walking-talking robo-pet. There is also a Master Build using as many as half a million bricks. But who will be crowned the winner for 2018? With guest judge Sue Perkins.

New host Nish Kumar presents a celebrity Christmas special, joined by regular judge Matthew Ashton and Amy Corbett from the US version of the show. The three teams are Taskmaster's Alex Horne and Sophie Duker, Sophie Ellis-Bextor and her two sons, and Scarlett Moffatt with her dad and sister. They must construct a wearable Lego Christmas jumper that can survive star jumps and the magical interior of a snowglobe.