The Master Builder is a character who leads the Builder Base of Clash of Clans, a dark village reached by canoe, which you must build to interconnect with your main village through the master builder, who will serve at some point in the game as the sixth builder in your main village.
What you need to do to unlock the Master Builder
He first appears in the Builder's Base Village tutorial as the Builder's Leader.
In order for this parallel village and with it the Master Builder to appear, you need to level up the town hall to level 4, and then rebuild the broken boat that appears on the shore of the lake which will allow you to go to the other side.