Time for the fun part. You're in the bathroom with the Book Man himself. Smash everything. Then send in the rat. Use a combination of rat and spells to move along.

Ride the plunger to get the final item, then use Harry to talk snaketongue - the door opens.

Go in!

Now you're in a big bone area.

Smash everything and turn bones into skeletons. Get the enemy on the left by plunging him. Then go right. Build various things including a bridge.

Ride up in the snake mouth to the right - now get to the door.

It's the final boss time, with the snake.

Have him blast away at you - standing in front of those colored rocks - to get the first two items for the pot. Now you need the "tooth".

Have the snake blast the rocks on the left. Then blast his tongue.

Now do 3/3 instrument building for a shield.

Go up on the left, use the pump, and hop into it to get to the sword area. Sword + snake head = end!

Lego Harry Potter Walkthrough