Okay I am combining the last two. I will fill it with lava, then cover it in obsidian and over that make a wool troll face on the roof, so when he does cut through he will be immediately greeted with an inaccessible house.
the best is u put TNT all though out the floor of the house were he cant see then you put red stone timer to when he walks in his door and the pressure plates that he has set to close the door goes off so does the TNT under his house.
